How to Gain Weight With A Fast Metabolism: 9 Science-Backed Tips

While many Americans may be looking to lose weight nowadays, there’s still a sizable population of people who struggle with the opposite problem: gaining weight.  

If you’re someone who falls into the latter category, chances are you’ve spent plenty of time trying to bulk up, only to find that the scale just won’t seem to budge no matter what you do – it can certainly be pretty frustrating, to say the least.       

And one of the first places many people point their fingers when they’re having trouble gaining weight is at their metabolism.  So what gives, can having a fast metabolism really make it more difficult to gain weight?  And if so, what can you do to start seeing more progress?  

How Do You Know If You Should Gain Weight?

One of the standard ways organizations like the National Institute of Health (NIH) determine whether or not an individual is underweight is by looking at their body mass index (BMI).

BMI is essentially a ratio of your weight to height, used to determine whether or not you’re at a healthy body weight.  A BMI that falls below 18.5 would be considered underweight for both men and women 20 and older.  

You can easily calculate yours with an online BMI calculator, or if you want to do it by hand, the formula is as follows: kg/m² (weight in kilograms divided by height in meters squared).

Even if you’re BMI is in the normal range though (18.5 - 24.9), you might still be able to benefit from gaining some weight.  For example, if you’re what’s known as skinny fat, you could potentially be at a healthy body weight based on your BMI, but in reality, have less lean muscle mass compared to what’s ideal.  

How Can Your Metabolism Affect Your Ability to Gain Weight?

While there are ultimately many things that can cause someone to be underweight, one of the primary culprits could be your metabolism.  

The term metabolism refers to the biochemical processes through which your body creates and burns up the energy (i.e. the calories) it needs to function.  The body uses up calories in numerous different ways and the rate at which each person ultimately expends energy (i.e. burns calories) varies.  

One of the most obvious ways that your body burns calories is through physical activity.  Whether it’s household chores or intense exercise, being active burns calories, and the more active you are, the more calories you’re going to burn.  

But even at rest, your body needs energy to keep things like your organs and all of the internal processes going on inside of you up and running.  The total number of calories it takes to do this is known as your basal metabolic rate (BMR). Your BMR is ultimately determined by your genetics and at the end of the day, some people naturally burn more calories at rest than others.

So, if you’re underweight and don’t have a lot of physical activity in your daily life, part of the problem could be that your BMR is higher than average. Though that might not be music to your ears, it certainly doesn’t mean that it’s impossible for you to gain weight.  

How to Gain Weight With a Fast Metabolism: 9 Science-Backed Tips

From developing a better understanding of how many calories you should be taking in on a daily basis to learning what kind of foods you should be eating, here are 9 science-back tips for gaining weight with a fast metabolism.  

1. Build a Calorie Surplus in Your Diet

If your goal is to gain weight, nothing is more important than a calorie surplus, which happens when you take in more calories than your body burns off in a day.  No matter how fast your metabolism is, if there’s a calorie surplus in your daily diet, you will gain weight.  

The first step in setting up a calorie surplus lies in determining how many calories your body actually burns off in a day – i.e. your total daily energy expenditure (TDEE).  Only when you know your TDEE will you be able to accurately adjust your calorie intake to see the kind of weight gain you’re after. 

You can easily estimate your TDEE using a free online calculator, which will give you a rough calculation of your daily calorie expenditure given things like your height, weight, age, and activity level.  

Once you have a number to work with as far as your TDEE goes, you can begin throwing some extra calories into your daily diet to create a calorie surplus.  The general rule of thumb is to consume somewhere around 500 extra calories per day, so if your TDEE is 2,000 calories then your daily calorie target would be 2,500.  

Again, the number you get from the TDEE calculator is only an estimate, and because we’re assuming you may have a faster than average metabolism, your may need to continue adjusting your calorie intake upward slightly until you see steady, consistent weight gain.  So, if we’re going with the above-mentioned example and 2,500 calories per day isn’t quite enough to see progress after a few weeks, then you’d go up to 2,600 and continue the process until you land in the right spot.  

2. Eat Plenty of Protein

On top of establishing a calorie surplus in your diet, another important aspect of your nutrition to focus on when you're trying to gain weight is your protein intake.  Protein plays a vital role in your body's production of new tissues -- especially muscle tissues, and without enough, it will be very difficult to improve your body composition, even if you do end up gaining weight.  

When most people say they want to gain weight, what they really mean, of course, is that they want to add lean muscle mass to their frame, not fat.  In order to do that though, you absolutely need to have enough protein in your daily diet (you also need to be working out, which we’ll talk more about below).  

So how much protein should you be consuming each day if you want to build muscle?  While there is no one specific number that is going to be ideal for everyone, the general rule of thumb has traditionally been to take in at least one gram of protein per pound of body weight.  So for example, if you weigh 140 lbs the goal would be to consume at least 140 g of protein each day.  

3. Don’t Skip Out on Carbs and Fat

While protein is certainly important when it comes to bulking up, you also need a well-balanced distribution of carbohydrates and fats in your diet in order to keep things healthy and consistent.  

Carbs are your body’s primary fuel source and should make up somewhere between 45 - 65% of all the calories you consume in your daily diet, according to organizations like the NIH. Without an adequate supply of carbs in your daily diet, it may be more difficult to summon the energy you need throughout the day to keep pushing.  

While it often gets a bad rap, dietary fat plays a number of important roles in the body, including helping you to absorb and break down numerous different vitamins and minerals.  In fact, without enough of it in your diet, not only would it be more difficult to gain weight but you’re also likely to develop vitamin and mineral deficiencies as well.  That’s why 20 - 35% of all your daily calories should come in the form of healthy fats.

4. Focus On Energy-Dense Foods

When it comes to gaining weight with a fast metabolism, it’s also important to obtain your calories from the right kinds of foods.  In general, that means healthy whole foods that are rich in nutrients and are energy-dense.  For example, you want to minimize highly processed foods that are high in things like sugar and instead focus on getting your carbs from healthy whole foods rich in complex carbs.  

On top of limiting things like sugary drinks and snacks in favor of more nutritious options, you also don’t want your diet to revolve too much around foods that are filling but don’t contain a lot of calories.  

For example, things like green vegetables have plenty of health benefits to offer, however, they also have a high water content and contain few calories, which means that eating too many of them can make you feel satiated without actually providing you with all that many calories.  

That’s obviously not what you want if you're trying to increase your calorie intake to gain weight.  If you’re underweight and have a fast metabolism, you want to make every meal count so that you’re sure you’ve taken in more calories than you’ve burned off in the day. 

Now that doesn’t mean you should never eat vegetables or other low-calorie foods if you’re trying to gain weight, but rather that the majority of the food you take in should come in the form of calorically dense, whole foods.

5. Eat Smaller Meals More Frequently

One of the issues many people face when they’re trying to gain weight is simply eating enough calories.  Even if you have a clear picture of your daily calorie target, actually hitting it can still be a daunting task, especially when you’re first starting out.  

However, one of the easiest ways to nail down your calorie surplus day in and day out is by eating smaller meals more frequently.  

For example, let’s say you're trying to eat 2,500 calories per day.  Instead of trying to squeeze all those calories into 2-3 meals per day – which can be tough if you’re not used to eating that much – splitting them up across 5-6 meals can be an easier way to get in all of the calories your calories without having to eat to the point of discomfort.

6. Resistance Training is Important

In addition to getting your diet and nutrition dialed in, resistance training is also important when it comes to gaining weight.  As we’ve already discussed, you want the majority of the weight you gain to come in the form of lean muscle mass, not fat, and in order for that to happen, you’ll need to be regularly lifting weights.

Resistance training helps to stimulate a biochemical process within your body known as muscle protein synthesis (MPS) and it’s through this general process that your body builds new muscle tissues.  

More specifically, lifting weights actually causes microscopic damage to your muscles, which your body must then repair.  In the right conditions – i.e. when there’s enough protein and calories coming in through your diet – your body can actually go in and rebuild the damaged muscles bigger and stronger than they were before.     

7. Don’t Go Crazy With Cardio

If you’re thinking about doing cardio while you’re trying to gain weight, there are a few things to consider.  First of all, performing cardio is going to increase your total daily energy expenditure, which can make it more difficult to gain weight.  So, you’ll definitely want to be weary of going too far overboard to the point that you're burning off more calories than you’re taking in through your diet.  

Also, if you do choose to do cardio, you’ll want to do it in a separate training session from your resistance training.  That’s because cardio can interfere with your ability to build muscle when it's performed back-to-back with resistance training.  Instead, save cardio and resistance training for different days, or at the very least, separate training sessions.  

8. Take the Right Supplements

On top of diet and exercise, another helpful tool for gaining weight with a fast metabolism can be supplementation.Whey protein, for instance, is a staple in countless boydbuilders’ arsenals not only because it makes hitting your daily protein goals a breeze, but also because it's amongst the highest quality proteins out there.

On top of that, other natural supplements like creatine, phosphatidic acid, and HICA can also help to improve your muscle-building potential and workout performance.  Once combined with a solid meal and training plan, supplements like these can help you to build significantly more muscle mass compared to diet and exercise alone.   

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9. Keep Up the Consistency and Track Your Progress

Now that we’ve gone over everything from diet and exercise to supplementation, our final tip is to keep up the consistency.  Once you’ve figured out what your calorie goals are, find ways to make sure that you're hitting them day in and day out.  And don’t forget to keep up with your training in the weight room – that means finding exercises that you enjoy doing and can stick with in the long term. 

The ultimate reality is that gaining weightthe right way takes time, and in order to find long-term success, you have to keep at it week after week and month after month.  On a good week you may only gain something like 1 pound, but after a few weeks and then a few months finally roll by, those incremental gains can turn into something substantial.  

One of the best ways to keep yourself going from week to week is to regularly track your progress.  Something as simple as seeing steady strength gains across your workout journal or seeing small but noticeable new developments in your progress pictures can be just the kind of motivation you need to keep yourself going when your end goal isn’t yet in sight.  

Wrap Up

If gaining weight has given you issues in the past, part of the problem could be your metabolism.  While it’s true that it can be more difficult for some people to gain weight it doesn’t mean that it’s impossible.

In order to see steady, consistent weight gain, you’ll not only need to understand what your body’s calories needs are and make sure that you’re taking in more calories than you’re burning off, but you’ll also need to follow a regular resistance training routine.  

On top of that, you’ll also need to consume plenty of protein along with a balanced distribution of all 3 macronutrients in your daily diet in order to see the most success when it comes to building muscle and minimizing fat gains.  

In addition to diet and exercise, taking supplements like whey, along with ergogenic aids like creatine and HICA, can also help improve your ability to gain weight.  

Lastly, consistency is key.  In order to see long-term success, you’ll need to find ways to keep up your eating regimen and develop a workout routine that you can stick with week after week and month after month.