As a concept, weight loss seems pretty simple: it happens when you take in less energy than your body burns off.  But in reality, many people ultimately struggle to achieve the types of weight loss outcomes they’re after, even when trying to be more conscious about their eating habits.  

That’s why in today’s day and age there are literally dozens of different diet plans specifically geared towards folks who are having trouble with weight loss.  But with all of the hype and over-the-top claims circulating around the internet, it can be difficult to tell which diets are for real and which ones aren’t.  

That’s why in this article, we’re evaluating the scientific findings surrounding a number of popular diets in order to shed some light on which weight-loss diets work best.  But before we dive into the findings, let’s first discuss how we actually went about assessing the diets included on this list.  

Evaluating the Efficacy of Different Weight Loss Diets

Through an investigation of the research findings surrounding a number of different popular weight-loss diets, we’ve developed a 4-star rating system (set up in half-star increments), with 1 star representing the most ineffective diets and 4 stars representing those with the most significant effects on weight loss.   

⭐ ☞ ⭐½ ☞ ⭐⭐ ☞ ⭐⭐½ ☞ ⭐⭐⭐ ☞ ⭐⭐⭐½ ☞ ⭐⭐⭐⭐

We took into consideration 3 separate factors in order to evaluate each diet’s overall effectiveness and ultimately identified 11 different diets with at least some scientific evidence of efficacy.  The factors we considered are as followed:

Factor #1: Effects on weight loss

Are there clinical trials that show a significant effect on weight loss?  Have any studies shown it to be ineffective?  Are there long-term trials (≥ 1 year) that show significant effects, or only short-term ones (< 6 months)?

We subtracted a half star from the diets ranking if there wasn’t much evidence from long-term studies.  We took away a full star if the effects of the diet on weight loss have only been shown to be moderately effective –i.e. it’s been directly compared to other diets and shown to be less effective.

Factor #2: are there other health benefits? 

Does research show that the diet may offer health benefits other than weight loss?  On the flip side, is there any evidence that it might also cause some adverse effects?

We took away half a star if research on long-term health outcomes is hard to come by — this doesn’t necessarily mean that the diet doesn’t offer other health benefits, but rather that these benefits have yet to be clearly demonstrated in reliable, longer-term studies.  

At least half of a star was subtracted if there wasn’t much research investigating the diet’s effects on things other than weight loss outcomes.  Finally, we also took away a ½ star if the diet was observed to have some potentially negative side effects.   

Factor #3: is the diet easy to stick to?

One of the biggest issues with weight loss is that even when it does occur in the short term, many people tend to regress over time, eventually regaining the weight that they lost.  That’s why we’ve also taken into consideration adherence rates from clinical trials in order to determine how difficult each diet is to stick to.  

We subtracted half of a star if clinical evidence showed that the diet was of medium difficulty to stick to — i.e. adherence rates weren’t abysmal but some participants did find compliance difficult.  We subtracted a full star if there was clear evidence that the diet is difficult to follow — i.e. low adherence rates have been routinely observed across multiple studies.  

What Are the Best Weight Loss Diets?

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1. The Atkins Diet

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How Does it Work?

The Atkins diet is a low-carb dietary approach that focuses on achieving positive weight loss outcomes by restricting your carbohydrate intake rather than your overall calorie intake — i.e. you won’t be counting calories on the Atkins diet.

You ‘ll be avoiding things like sugar, grains, starches, and even certain high-carb vegetables on the Atkins diet.  While you’ll be consuming more fat in your diet to replace the missing carbs, you’ll be steering clear of unhealthy fats like trans fats.

Some versions of the Atkins diet — particularly the Modified Atkins diet, which places a more extreme limitation on carbs — have been reported to induce ketosis, which is the process through which the body mobilizes fat stores to be burned up as energy.  

However, most people on the regular Atkins diet likely won’t be eating few enough carbs to enter into ketosis (we’ll dive deeper into the topic of ketosis when we cover the ketogenic diet).  

Effects on Weight Loss

The Atkins diet has been well-researched and to date, numerous randomized controlled trials (RCTs) have demonstrated that regular adherence can induce significant amounts of weight loss.  

For example, one such study published in the New England Journal of Medicine ultimately found that participants on the Atkins diet saw an average reduction in body weight (BW) of 6.8% over the course of 3 months.(1)

On top of that, the researchers also found that those on the Atkins diet lost significantly more weight in comparison to those who were placed on a conventional low-fat, high-carb diet ( – 6.8% BW vs. –2.7% BW respectively)

In fact, several studies comparing the Atkins diet to other popular weight-loss diets have ultimately found that adherence to the Atkins diet, on average, resulted in the most weight loss.(2)

For example, one 2017 systematic review evaluating the effects of 7 different popular weight-loss diets (Atkins, DASH, Ornish, Mediterranean, Zone, Paleolithic and Glycemic-Index) ultimately found that the Atkins diet produced the most significant weight loss outcomes across the 16 different studies included in the review.(3)

The researchers did point out that these findings may be, at least, partially due to the fact that many other diets have not been researched as extensively as the Atkins diet.  However, whatever the case may be, there is still an ample body of evidence that regular adherence to the Atkins diet can lead to significant amounts of weight loss.

Other Health Benefits

There is an ample body of evidence that regular adherence to the Atkins diet can significantly improve a number of different metabolic markers, including glucose metabolism, total, LDL, and HDL cholesterol. (4)(5)

Other research has also demonstrated that long-term compliance with a low-carb diet like the Atkins diet is significantly associated with a reduced risk of cardiovascular disease. (6) 

Is it Easy to Stick to?

While regular adherence to the Atkins diet can certainly lead to weight loss, research does show that it may be a somewhat challenging diet to stick to, with weight regain being a common occurrence in long-term studies.

For example, one randomized controlled trial ultimately found that compared to those on a conventional diet, individuals following the Atkins diet were significantly more likely to experience weight regain at the 1-year mark of the study, leading the researchers to conclude that long-term adherence to the diet may be relatively difficult.(7) 

Another 2008 study ultimately found that while close adherence to the Atkins diet was strongly associated with weight loss, almost half of the study participants who were placed on the Atkins diet were no longer regularly following the diet 12 months into the study, also suggesting that it may not be the easiest diet to stick to in the long-term.(8)

2. DASH diet

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How Does it Work?

The DASH diet, which stands for Dietary Approaches to Stop Hypertension, is oriented around foods like vegetables, lean meats, fruits, whole grains, beans, nuts, and low-fat dairy products. 

It emphasizes the importance of nutrients like protein, calcium, fiber, and potassium in your daily diet and also places limitations on your intake of saturated fat and sugar.  

Some research also suggests that the DASH diet may be even more effective when your sodium intake is reduced, however, not all approaches are low-sodium.  

Effects on Weight Loss

To date, most research involving the DASH diet and weight loss has demonstrated positive results.  For example, one 2014 study involving individuals with an increased risk of obesity and diabetes ultimately found that compared to a control group who experienced no weight changes, those who underwent a 12-week DASH dietary intervention ultimately saw an average weight reduction of 7 pounds. (9) 

Another 2016 review involving 10 different randomized controlled trials ultimately found that compared to the control groups in the included studies, participants on the DASH diet lost significantly more weight over the course of 8 – 24 weeks.(10)

In a longer-term 2007 study, the researchers ultimately found that at an average follow up of 1.75 years, those who had regularly adhered to the DASH diet had lost an average of 10.8 pounds(11) 

Other Health Benefits

As a dietary intervention originally designed to combat hypertension, there is an ample body of evidence that the DASH diet can help to reduce both systolic and diastolic pressure.(12)

A number of studies have also demonstrated that the DASH diet can help to decrease the risk of metabolic syndrome.  In addition to reducing fasting insulin concentrations, adherence to the DASH diet has also been shown to improve total and HDL cholesterol, reduce serum triglycerides and decrease both systolic and diastolic blood pressure.(13)(14)

Is it Easy to Stick to?

Research shows that the DASH diet has relatively high retention rates both in the short and long terms, suggesting that it may be an easier diet to stick to.  For example, one short-term 2010 study ultimately demonstrated a 74% retention rate over the course of a 12-week DASH dietary intervention.(15)

Another long-term study eventually found that after an average follow up of two and a half years, 81% of those who had been assigned to the DASH diet had maintained significant amounts of weight loss, with the average participant demonstrating a 5.3% reduction in body weight from baseline.(16)

3. Intermittent Fasting

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How Does it Work?

Intermittent fasting is a dietary approach that incorporates extended periods of no food intake into your regular eating routine.  In other words, instead of the average 3-meal-a-day eating schedule, you’ll be following a stricter schedule with longer gaps in between meals, although there are no limitations on specific foods per se.    

There are many different approaches to intermittent fasting.  It can be as simple as skipping breakfast so that you’re fasting for the first 8 hours of each day. 

Or you could also take a slightly more complex approach like alternate day fasting, which entails shifting between normal feeding days and days in which your feeding window is severely restricted — with 5:2 fasting, for example, you’ll drastically reduce your eating window and calorie intake twice a week, while the other 5 days you’ll be eating normally.  

Effects on Weight Loss

While long-term research on intermittent fasting is still somewhat underdeveloped, numerous human trials have demonstrated significant effects on weight loss in the short term. (17)

For instance, one 2018 study compared the effects of intermittent fasting versus a traditional energy restriction on weight loss.(18)  The intermittent fasting group consumed around 500 calories two non-consecutive days per week; the other days they ate normally. Those in the continuous energy restriction group maintained a reduced energy intake (26-28% calorie reduction) every day over the course of 6 months.  

At the conclusion of the study, the researchers found that weight loss was similar in both groups, with the fasting group losing an average of 17.6 lbs compared to 19.8 lbs for those on the continuous energy restriction.   

Another 2016 review involving several relatively recent short-term studies on alternate day fasting ultimately found significant effects on weight loss and body fat across all of the included studies, with participants seeing an average reduction of 3 – 7% in body weight and 6.6 – 12.1 pounds in body fat.(19)

Other Health Benefits

In addition to promoting weight loss, intermittent fasting may also help to improve several aspects of your metabolic health.  Research findings suggest that regular adherence to an intermittent fasting diet is closely associated with improvements in glucose homeostasis and insulin sensitivity.(20)

Furthermore, several clinical trials have also demonstrated that intermittent fasting may help to reduce inflammation, total cholesterol, oxidative stress, and blood pressure, especially in overweight and obese individuals.(21)(22)  

Is It Easy to Stick to?

When it comes to long-term adherence rates, reliable data is hard to come by, however, short-term findings suggest that intermittent fasting is likely of medium-difficult as far as compliance goes (depending on the method you use).  

Several studies have shown that compared to individuals on a continuous energy restriction, those on an intermittent fasting diet have higher rates of self-reported hunger, which may ultimately make longer-term compliance slightly more challenging.(23)

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4. The Keto Diet

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How Does it Work?

The ketogenic (keto) diet is a low-carb, high-fat, moderate-protein diet.  While there is no one standard macronutrient ratio for keto, general recommendations are usually somewhere around 5-10% of your calories coming from carbs (usually ≤ 50 g per day), 20 – 30% from protein, and 70 – 80% from healthy fats — though you’ll be limiting your intake of things like trans and saturated fats.  

The goal of the ketogenic diet is to put your body into ketosis, which is a physiological process through which the body shifts over to converting fats stores into useable energy — when carbs are severely restricted in your diet, your body turns to converting fat into energy. In this state, the body converts fatty acids into ketones, which are then burnt up as fuel.    

Effects on Weight Loss

Numerous short and longer-term studies have demonstrated that regular adherence to the ketogenic diet can lead to significant amounts of weight loss, with one 2014 review ultimately concluding that it is undoubtedly an effective tool for fighting obesity.(24)

Short term studies comparing the ketogenic diet to high-carb, low-fat diets, have found that keto helped to reduce hunger and food intake to a greater degree, leading to more weight loss in comparison to those on more traditional diets.(25)(26)

A longer-term study comparing the ketogenic diet to a traditional low-calorie diet also found that keto was more effective at inducing weight loss, with most participants in the keto group seeing an over 10% reduction in body weight.(27)  

On top of that, the researchers also found that lean mass was well-preserved amongst those on the keto diet, suggesting that most of their weight loss came from body fat, rather than lean mass.  

Other Health Benefits

A number of studies have shown that the ketogenic diet can improve several metabolic parameters to a greater degree than a standard hypocaloric diet.(28)

In addition to demonstrating a significant decrease in total and LDL cholesterol, researchers have also found that a very low-carb, ketogenic diet helps to improve HDL cholesterol along with triglycerides, and blood glucose levels as well. (29)(30)

Is it Easy to Stick to?

Research shows that the ketogenic diet may be a challenging diet to stick to.  For example, one 2015 review involving 12 different studies ultimately found only a 45% compliance rate amongst those on the ketogenic diet, compared to a 56% compliance rate for individuals following the similar, but less extreme, Atkins diet.(31)

5. The LEARN Diet

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How Does it Work?

LEARN is an acronym that stands for lifestyle, exercise, attitudes, relationships, and nutrition.  As you may be able to tell, it doesn’t only encompass a dietary protocol, but also a number of lifestyle and behavior modification as well, including the addition of exercise into your regular routine.  

On the nutrition side of things, the LEARN diet is a high-carb, low-fat, hypocaloric diet that doesn’t necessarily limit any type of food per se, however, it stresses the importance of knowing your calorie and macronutrient requirements along with making overall healthy food choices.  

Effects on Weight Loss

To date, the LEARN diet appears to be moderately effective for weight loss.  While multiple studies have demonstrated significant findings, most of those studies also showed that other diets worked better.  

For instance, one 12-month trial comparing the effects of several popular weight-loss diets, including the LEARN, Atkins, Zone, and Ornish diets, ultimately found that individuals on the LEARN diet lost the 2nd least amount of weight, with participants only losing about 5.7 pounds over the course of 12 months.(32)

Another 2014 study comparing the effects of the LEARN diet (high-carb, low-fat) to a high-fat diet ultimately found that those on the high-carb diet ultimately saw significantly less weight loss both (–17.6 lbs vs –19.2 lbs) after 6 months of dieting.(33)

Other Health Benefits

Like with many weight-loss diets, the LEARN diet is purported to improve several metabolic parameters, however, to date, there is not enough reliable research on its metabolic effects to say for sure whether or not this is, in fact, the case.  

Is it Easy to Stick to?

Studies evaluating compliance are lacking, however, as an approach that makes changes to your entire lifestyle rather than just your diet, it’s safe to assume that the LEARN diet may be more difficult to follow than the average diet.  

6. The Mediterranean Diet

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How Does it Work?

The Mediterranean diet is based around the main food sources consumed by the people living around the Mediterranean sea in the 1960s.  It doesn’t necessarily entail any kind of calorie counting, but rather, seeks to naturally reduce your calorie intake through the types of foods you eat.  

The Mediterranean diet eliminates processed foods, which weren’t widely available in Southern Europe back in the 60s. The foods that you can eat are broken down into three basic categories: everyday foods, foods you can eat a few times a week, and foods you can eat only occasionally.  

Main every day foods include vegetables, fruit, whole grain cereals (pasta, rice, oats, etc.) olive oil, dairy-based foods (cheese, yogurt, etc.), nuts, seeds, herbs, and spices.  Foods you can eat a few times a week include lean meats, fish, eggs, potatoes, and beans.  Occasional foods like soda, fruit juice, cake, and pie — anything with lots of sugar and/or trans fats — should be kept to less than 2 servings per week.  

Effects on Weight Loss

Countless studies have demonstrated that the Mediterranean diet can lead to significant amounts of weight loss, even in the instance in which study participants’ calorie intakes were not directly restricted in the study.    

For instance, one meta-analysis of 16 different Mediterranean diet trials in which participants’ calories were unrestricted ultimately found a significant amount of weight loss across all of the included studies, with participants losing an average of about 4 pounds.(34)

When the diet was combined with a calorie restriction, participants lost even more weight; in the same meta-analysis, the researchers ultimately observed an almost 9-pound weight reduction across 4 different Mediterranean diet trials in which participants’ energy intakes were also restricted.    

There is also plenty of evidence that the Mediterranean diet may be an effective long-term approach to weight loss as well.  For instance, one 2016 systematic review ultimately found that compared to a low-fat diet, individuals on the Mediterranean diet lost significantly more weight at 12+ months of dieting (–8.7 lbs vs –15.6 lbs respectively).(35)

Other Health Benefits

There is an ample amount of evidence that regular adherence to the Mediterranean diet can help to improve several metabolic parameters including total and LDL cholesterol, triglycerides, insulin sensitivity, and fasting glucose.(36)  It’s also been shown to positively impact several cardiovascular risk factors, like your lipid levels and blood pressure as well.(37)

Several studies have also demonstrated significant reductions in inflammation, even in the absence of weight loss; however, greater improvements in inflammation levels have been observed in combination when individuals on the Mediterranean diet also lost weight.(38)  

A 2008 meta-analysis of 12 different long-term studies involving follow-ups ranging from 3 to 18 years ultimately found a significant improvement in health status amongst individuals with a high adherence to the Mediterranean diet.(39)  

In addition to finding significant reductions in mortality from cardiovascular disease and cancer, the researchers also found that those with greater adherence to the Mediterranean diet also had significantly lower incidences of diseases like Alzheimer’s and Parkinson’s as well.   

Is it Easy to Stick to?

The Meditteranean diet appears to be a comparatively easy diet to stick to.  Several longer-term studies have demonstrated relatively high compliance rates, with many participants maintaining or even improving on their weight loss outcomes in long-term follow-ups.(40)  

For instance, one 2015 review of 13 other studies and meta-analyses ultimately found that in follow-ups ranging from 2 to 5 years, those on the Meditteranean diet, on average, were still down a significant amount of weight compared to baseline, with a significantly increased probability of remission from metabolic syndrome. (41)

7. The Ornish Diet

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How Does it Work?

The Ornish Diet is a predominantly plant-based diet developed by Dr. Dean Ornish.  Main food sources include vegetables, fruits, whole grain cereals, soy-based foods, low-fat dairy products (cheese, yogurt, etc.)  legumes, and eggs.  Meat, fish, and poultry, on the other hand, are off-limits.    

Your calories are generally unrestricted on the Ornish diet, although it does promote portion control.  On top of that, it’s also recommended that your meals are split up into smaller portions eaten more frequently throughout the day in order to reduce hunger.    

Effects on Weight Loss

Several studies involving the Ornish diet have demonstrated statistically significant findings.  For example, one study published in the Journal of the American Medical Association ultimately found that participants on the Ornish Diet lost an average of 7.3 lbs over the course of 12 months.(42)   

However, to date, research suggests that compared to some other diets, the Ornish diet may only be moderately effective when it comes to weight loss.  

For example, one study comparing 4 different weight-loss diets (Ornish, LEARN, Zone, and Atkins) ultimately found that while those on the Ornish diet did lose significant amounts of weight over the course of the 1-year study (–4.8 lbs), most of the other diet groups lost significantly more weight in the same time period.(43)

Other Health Benefits

Some research has shown that like other plant-based diets, the Ornish diet may help to reduce several cardiovascular risk factors.(44)  However, to date, there aren’t many reliable studies that directly evaluate the Ornish diet — i.e. there is plenty of evidence that a basic vegetarian diet can reduce the risk of cardiovascular disease, however, few if any randomized controlled trials have evaluated how the specific protocol of the Ornish diet affects cardiovascular health.  

Is it Easy to Stick to?

According to one 2008 review which evaluated adherence rates for a number of different weight-loss diets, the Ornish diet is likely a difficult diet to follow when it comes to closely adhering to the guidelines.(45)

For example, One 2005 study ultimately found that after one year, only 50% of participants who were originally assigned to the Ornish diet were still regularly following the dietary protocols.(46) 

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8. The Paleo Diet

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How Does it Work?

The paleo diet is based on the nutritional habits of our paleolithic ancestors, who without farming capabilities, had to depend on the nutritional resources that were available to them in their geographic location. 

The paleo diet eliminates things like grains, dairy products, and processed foods, which simply were not around during the paleolithic period.  Instead, it is centered around healthy, whole foods like meat, poultry, eggs, fish, vegetables, herbs, fruits, nuts, seeds, and healthy oils.  

The paleo diet doesn’t necessarily require that you count calories or macronutrients, with the inherent assumption being that eating healthy, whole foods will naturally reduce your calorie intake.    

Effects on Weight Loss

Research has consistently demonstrated that the Paleo diet can be an effective tool for weight loss.  For example, at the conclusion of one short-term study where participants underwent a paleo diet intervention, the researchers ultimately observed an average weight reduction of over 5 pounds over the course of only 3 weeks.(47)

Findings from longer-term studies also show significant effects on weight loss.  For instance, one 2019 meta-analysis including studies with follow-ups greater than 6 months ultimately found that those on the paleo diet, on average, were still down significant amounts of weight at the time of the follow-up.(48)

Other Health Benefits

Like with many of the other diets on this list, there is strong evidence that regular adherence to the paleo diet can improve multiple aspects of your metabolic and cardiovascular health.  

For instance, one meta-analysis involving four different studies ultimately found significant improvements in systolic and diastolic blood pressure, fasting blood sugar, triglycerides, and total, LDL, HDL cholesterol.(49) 

A 2015 study demonstrated similar improvements in metabolic markers independent of changes in weight loss, leading the researchers to conclude that the paleo diet may help to improve metabolic markers in individuals who weren’t able to achieve favorable changes through other “heart-healthy” diets.(50)  

Is it Easy to Stick to?

Longer-term research shows that the diet is likely of medium difficulty when it comes to compliance.  Although participants in trials of longer duration still achieved significant weight loss, reduction in weight tended to decrease over time, suggesting that high-compliance in the long term may be more challenging than some of the other diets on this list.(51)  

9. Plant-Based Diets (Vegan/Vegetarian)

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How Does it Work?

Vegetarianism and veganism both eliminate meat, poultry, and fish from the diet, however, while the vegetarian diet allows for animal-derived foods like eggs, honey, and dairy products, for example, animal-based products of any kind are prohibited on the vegan diet.  

While there is no one standard approach as far as macronutrients are concerned, many studies involving vegetarian/vegan diets and weight loss have tended to employ a low-fat approach.

Effects on Weight Loss

Both the vegetarian and vegan diets have been shown to have significant effects on weight loss, even in the absence of a calorie restriction.  

For example, one 2014 study published in Nutrition Research ultimately found that compared to a standard low-calorie diet, participants on a non-calorie-restricted vegan diet consumed almost 300 calories less per day, leading to significantly more weight loss over the course of three months (although both dieting groups lost similar amounts of weight by the 6-month mark).(52)

Another longer-term study comparing the effects of an unrestricted vegan diet to a low calorie, low-fat diet, ultimately found that those on the vegan diet lost significantly more weight after one year of dieting (–11 lbs vs –4 lbs).  While both groups saw a regression in the second year, the vegan dieters still ultimately saw a greater decrease from baseline in comparison to those on a low-calorie, low-fat diet (–7 lbs vs –2 lbs).(53)

Several studies have shown that a vegetarian diet can also lead to significant amounts of weight loss even in the absence of an energy restriction as well.  For example, one 2015 meta-analysis including 12 different randomized controlled trials found that those following a non-calorie restricted vegetarian diet saw an average weight reduction of almost 5 pounds over the course of a medium duration of 18 weeks.(54)

The researchers also found that those who consumed a vegetarian diet in combination with an energy restriction lost even more weight — subjects whose diets were also energy-restricted lost an average of almost 5 pounds more in comparison to those whose calorie intakes were not limited.  

Other Health Benefits

Preliminary evidence — mostly from short-term trials — suggests that a vegetarian/vegan diet may reduce the risk of cardiovascular disease and morbidity, however, more research needs to be conducted on long-term clinical outcomes before more definitive conclusions can be made.(55)

With that being said, several studies have demonstrated that a plant-based diet can significantly improve several aspects of metabolic and cardiovascular health, including total and LDL cholesterol, glycemic control, and glucose metabolism, at least in the short-term.(56)

While the benefits appear to be mostly positive, research does show that a plant-based diet can increase the chances of having certain micronutrient deficiencies which can, in turn, may increase the chances of adverse health outcomes.(57)

That’s why many nutritional experts recommend supplementing with things like vitamin B12, vitamin D, calcium, zinc, magnesium, and folic acid to those on plant-based diets.(58)

Is it Easy to Stick to?

Research shows that plant-based diets — particularly the vegan diet — may be difficult to stick to, especially for those who are following them to lose weight as opposed to for moral reasons.  

For example, one 2014 study ultimately found a 67% attrition rate amongst individuals on the vegan diet after only six months.(59)

Another longer-term study found that while those on the vegan diet lost significant amounts of weight after 2 years (– 6.8 lbs), they also gained back a significant amount of weight in between year one and year two (4 lbs), suggesting that long-term adherence was relatively difficult.(60)  

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10. WW (Weight Watchers)

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How Does it Work?

The Weight Watchers (WW) diet, is a comprehensive diet plan that also involves regular counseling.  While Weight Watchers doesn’t necessarily forbid any specific kinds of foods or direct people on exactly what to eat, there are still rules to follow.  

The dietary guidelines revolve around making healthy food choices, using portion control, and maintaining a calorie deficit.  Instead of counting calories and macronutrients, the WW diet makes use of a simplified points system, where things like calories, protein, sugar, and saturated fat are all broken down into point values — you’ll be allotted a certain amount of daily points based on your goals and background.    

Effects on Weight Loss

The Weight Watchers diet has been shown to be an effective agent for weight loss in multiple short and long term randomized controlled trials.   For instance, a 2011 study ultimately found that after 12 weeks of dieting, those on the Weight Watchers diet lost an average of almost 12 pounds, with 57% of the group seeing more than a 5% reduction in body weight.(61)

As far as long-term research goes, one study published in the Journal of the American Medical Association also found significant effects on weight loss, with those on the Weight Watchers diet losing an average of 6.6 pounds at the end of 1 year.(62)

A systematic review involving 3 different randomized control trials ultimately demonstrated significant amounts of weight loss (subjects were down an average of 3.2% in body weight) at the 2-year mark.(63)

Other Health Benefits

Most clinical trials involving the Weight Watchers diet have examined its effects on weight loss; few if any reliable studies have investigated its impact on other factors such as metabolic health markers.  However, with that being said, it is reasonable to assume that in tandem with weight loss, you’ll also likely see improvements in metabolic health.  

One of the potential downsides to the Weight Watchers diet is that there is a lot of flexibility in terms of what you can eat.  While that’s not inherently a bad thing, it does potentially increase the risk of your diet being unhealthy.   

In other words, you could be seeing significant amounts of weight loss on the Weight Watchers diet because your calorie intake is dialed in, but if your distribution of micro and macronutrients is off, it can be detrimental to your health.  

With that being said, the counseling aspect of the Weight Watchers diet can help you to assure that you are getting a healthy supply of the nutrients your body needs to properly function.  

Is it Easy to Stick to?

Research findings are scarce when it comes to compliance rates, however, based on the evidence that is out there, the Weight Watchers diet doesn’t appear to be an incredibly difficult diet to stick to.  For example, one 2005 study ultimately found that 65% of study participants on the Weight Watchers successfully completed the one year trial.(64)     

Findings from long-term studies suggest that while rates of high compliance tended to drop after a few months, most people were still down significant (though unremarkable) amounts of weight multiple years after beginning the Weight Watchers diet.   

11. The Zone Diet

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How Does it Work?

The Zone diet entails a specific approach to nutrition developed to better control the body’s inflammatory response.  Through the foods you eat, the Zone diet is designed to reduce your baseline levels of inflammation — research in epigenetics shows that your diet can actually change the ways in which your genes behave, potentially altering your body’s inflammatory response depending on what you eat.   

The Zone diet revolves around strict macronutritonal guidelines, with 30% of your total daily calories coming from protein, 30% from healthy fats, and 40% from carbohydrates, although grains and starches are only to be eaten in moderation.  On top of that, it’s also required that each meal you eat has a precise 0.75 protein to carbohydrate ratio.  

Effects on Weight Loss

There is indeed some evidence that the Zone diet can significantly impact the weight loss process, however, according to one review published in the International Journal of Obesity, of the few randomized trials that have been conducted, most have only demonstrated moderate effects.(65)

For example, one 12-month study comparing the effects of 4 different weight-loss diets, ultimately found that while the Zone diet lead to significant amounts of weight loss after 1 year, it ultimately resulted in the least amount of weight loss out of all of the diets included in the study (–3.5 lbs).(66)  

Other Health Benefits

While the Zone diet was specifically developed as a means to reduce inflammation, there doesn’t appear to be any reliable research examining whether or not this is actually the case.(67)   To date, there also hasn’t been much investigation into its effects on other metabolic and cardiovascular health markers either.   

Is it Easy to Stick to?

Few if any studies have directly addressed the issue of compliance.  One study did find that over 60% of those following the Zone diet were able to complete a 1-year trial, however, the researchers did not attempt to measure how closely the participants actually adhered to the diet over the course of the study.(68)

With that being said, based on the strict macronutritional requirements and limitations on things like grains and starches, it’s safe to say the Zone diet is likely more difficult than the average diet when it comes to sticking with it.   

Wrap Up

There you have it, 11 different weight-loss diets with at least some evidence of clinical efficacy.  While all of the diets on this list can be effective for short term weight loss — especially in combination with a calorie restriction — finding the diet that is going to produce the most weight loss in the long term ultimately depends on finding something that aligns with your personal goals and preferences.    

If you’re someone that enjoys rising to the challenge, maybe a diet that includes stricter nutritional guidelines or full-fledged lifestyle changes is for you.  If you’re looking for something that doesn’t turn your whole world upside down, on the other hand, finding a diet that doesn’t drastically restrict your food choices or alter your day-to-day life may be the best route.