Many people can find it a struggle to gain weight.

Being underweight and wanting to build muscle are the primary reasons to gain weight.

High energy use or lack of appetite are the common barriers to gaining weight.

Several methods can be employed; eating more food, eating more high-calorie food, adding calories to an existing food, eating less food but more often, liquid calories.

There are several pitfalls that can hamper progress.

How To Gain Weight

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​Why Gain Weight?

All talk and focus seem to be on losing weight, but this can hide the plight of the many who not only want to know how to gain weight but also struggle to do so.

The two common reasons for wanting to gain weight are due to being underweight and wanting to build muscle. And while it can be granted that little sympathy is warranted for those wanting to build muscle, the same cannot be said for those being underweight.

​Being Underweight

There are various potential health issues with being underweight, from weakened bones to fertility problems, but the two overriding reasons are nutritional deficiencies and a weakened immune system, both of which can become serious.

Ongoing nutritional deficiencies are likely responsible for a large percentage of the detrimental effects of being underweight. And being severely underweight over the long term can lead to muscle and even organ wastage.

A good indicator of being underweight is ongoing low energy and feeling tired. However, although these indicators are good they’re not necessarily reliable since we acclimatise to our conditions and can end up thinking they’re ‘normal’.

A reliable indicator in many is sleep problems. And it’s not necessarily falling asleep but rather staying asleep; routinely and inexplicably waking up at 3 am or something and being wide awake and alert is a pretty good and reliable sign that you need to consume more calories (although not the only reason, obviously).

​Building Muscle

The other common reason for needing to gain weight is to build muscle.

Muscle is a costly tissue, to both build it and maintain it, and we need a surplus of energy to build it in the first place.

This means that, if we don’t have a surplus of fat on us, we will need to eat in a slight calorie surplus to supply the energy our bodies need to construct the new tissue.

​Problems People Have Gaining Weight

Of course, the idea of gaining weight sounds so easy to a lot of us, and many people have no problems with it if they don’t pay attention to what they’re doing.

But other people do have problems, and gaining weight for these people can be difficult. There are two main reasons for this:

Lack of appetite.

High metabolism.

I guess a third could be that you have both of these problems, but really it can all be bundled under a lack of appetite because whether you have a high metabolism or not, if you find yourself unable to eat enough to gain weight then that’s simply a lack of appetite necessary to do so against the backdrop of whatever your energy expenditure happens to be.

​The Cure For Lack Of Appetite

You won’t like this, but the cure for a lack of appetite is to basically force-feed for a while, perhaps a couple of weeks.

At the start, your body might protest and be reluctant to take in these additional calories, especially if you bumped them up too fast, but this is only temporary and after some time it’ll get used to it and become comfortable with having more calories presented to it.

An important point here is that ‘force-feeding’ isn’t to say you should force-feed yourself to the tune of an additional several thousand calories every day and end up putting on a whole bunch of fat (and continually feeling sick in the process). The idea is to gain weight slowly, but reliably.

The amount of calories required to do this is somewhat dependent on the individual, but 250–500 calories above maintenance will be a good range for many people to start gaining weight.

Lastly, there’s no harm in going slowly, and can even be very worthwhile if you’re someone who ends up needing to bump their calories up a lot. Do this by introducing, say, 150–200 additional calories into your daily diet. Do this for a week. Then introduce another 150–200 calories. Repeat until you’re reliably gaining weight.

​High Metabolism

A high, or fast, metabolism, is just the term used to describe the people whose bodies use more energy by default. Our bodies use energy for basically everything that happens, and the bodies of those with a fast metabolism are just using more of it.

The mechanisms for this are not entirely clear, although a high level of NEAT (Non-Exercise Activity Thermogenesis) does appear to play a large role. This is the energy used during subconscious movements, such as fidgeting, talking with the hands, etc.

It sounds innocuous, but it can account for several hundred additional calories a day, which is more than your average gym session.

Another reason for a seemingly high metabolism is high NEPA (Non-Exercise Physical Activity), which is movement that isn’t dedicated to exercise, such as standing up, walking around etc.

NEAT is likely not modifiable, but NEPA is very modifiable as it’s a consequence of just deliberately moving more—or, perhaps in our case here, deliberately moving less. So chill out and relax, you’ll burn considerably less energy.

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​How To Gain Weight

We’re going to focus on consuming more calories and ignore the moving less option since moving less is seldom a sensible recommendation.

There are 5 good ways of getting more calories in.

Eat More Food.

Eat More High-Calorie Food.

Eat Little and Often.

Add Calories To Things.

Liquid Calories.

​Eat More Food

This is obvious, and it should also go without saying that you ideally want to do this by eating whole foods because they have more nutrition per calorie.

High palatability is what you want to look at here because there’s more chance you’ll want to eat more of it. So if it’s rice you like then eat more rice. If potato eat more potato. If pasta, eat more pasta.

Indeed, starch, of any variety, is often a good option because most of us like eating a lot of it. Just like we enjoy eating a lot of fat. Mix them together and it’s even better!

That said, we don’t need to become too fixated on whole foods, and if your diet is 80%+ whole foods then having the remaining ~20% as things that are less than ideal is okay.

Further, if we have some aversion to food then high palatability can be extremely important because job one is to attenuate your aversion to food in the first place—only then can we ever hope to get you eating properly again.

However, ‘eating more’ doesn’t often sit well with those who are struggling to gain weight because lacking the desire to eat is often the problem.

​Eat More High-Calorie Dense Food

The answer here then is to try eating the same amount of food but slanting your food choices into those foods that have more calories.

High-calorie dense food is less voluminous per calorie, therefore inherently less satiating per calorie, which allows us to eat more of it.

Fat is the most common option, and for good reason, it has the highest calorie density of all nutrients—so eat more fat, ideally unsaturated fat.

Another, and somewhat different idea towards doing this is to take out the satiation component of certain foods, such as those with skin. Consider potatoes: We can eat them with the skin or without, and while the skin of potato has a whole bunch of goodness in it, it’s also the most satiating component per calorie due to the fibre content. So not eating the skin will allow us to eat more of the potato, therefore getting more total calories in.

Now of course, we don’t want to go overboard with this idea of eating high-calorie dense food. Taken to the extreme we’ll just end up eating a whole bunch of fat and no fruit or vegetables, which isn’t a good idea at all.

But we can slant our food choices into higher calories. If you like fruit and nut, eat more nut. If you like fruit and yoghurt, eat more (full fat) yoghurt (tinned and/or dried fruit is also excellent for higher calories). If you like cheese and crackers, eat more cheese. If you like meat, eat higher-fat meat (like salmon). Etc.

Slanting our food choices into higher calories is not unhealthy, it only potentially becomes unhealthy when we have an excess amount of body fat on us in the first place—and what’s unhealthy here is the adding of even more fat onto our bodies, not the actual higher calories in the food.

Don’t play down this idea thinking it’s not very effective. It can be extremely effective. What we’re trying to do is nudge our calories up. And, due to your low appetite, the more imperceptibly we can do this the better.

You may only need to nudge your calorie intake up by a couple of hundred calories on a daily basis to start gaining the weight you need or want, and that can be easy to do almost without noticing it using this method.

​Eat Little and Often

Like all these points, this one can be incorporated with any of the others and none of them has to be used in isolation.

The reasoning behind this idea is that you may find it easier to get in more calories throughout the day since it could be large meals you have trouble with, not actually the large amount of calories per se.

For example, if a 1000-calorie meal leaves you feeling full for hours, but two 650-calorie meals can be eaten a lot more readily, then the two-meal option is the better choice for getting in more calories.

A point to note here though is that the little and often option ends up making some people eat fewer calories because they’re routinely full and not wanting to eat. If you notice this being you then obviously little and often is not a good idea in your situation.

​Add Calories To Things

This can require some thinking, and even a little creativity. What you do here is largely down to personal preference and what you like, but here are some examples:

Add cheese to things, such as soup.

Add nuts and nut butters to things.

Add seeds to things.

Add honey to things.

Add fat to things, such as bread/toast, potato. Add both fat and milk to mashed potato.

Make things with full fat milk (or coconut milk) instead of water, e.g. porridge, smoothies.

Add oil (olive, flax) to vegetables and salads.

Add dips to snacks, e.g. cucumber.

Add calories to fruit, e.g. cheese and apple, peanut butter and banana, honey and strawberries.

Every lick and bite of anything is going to contain calories, so 20–50 calories here and there can very quickly add up to hundreds over the course of a day.

​Liquid Calories

If, even after trying all of the above, you’re still struggling to get enough calories to gain weight, then you may want to look into liquid calories.

Liquid calories allow you to get down calories a lot easier. And they can pack a hell of a punch.

There’s various ways to get liquid calories, and you’ve probably seen the ‘mass gainer’ shakes and stuff like that on the market, but I don’t actually recommend these as they’re just simple carbs, which lack nutrition. A better and healthier alternative is the following:

Start with a protein powder base (choose a flavour you fancy).

Then just add calories to it: avocado, dark chocolate, nut butters, oil, fruit, oats, etc. Even a bit of cream or ice-cream can be added to it.

The shake can be made with milk or coconut milk instead of water for yet more calories.

The calories that can be added in this way are pretty high, so take a little care with doing it as adding one or even two thousand additional calories is pretty easy—we don’t want to go overboard and start gaining excessive amounts of fat.

Other examples of liquid calories are smoothies and juices. A fruit juice can even be considered one of your five a day—but only once as after the first one it doesn’t count.

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​Pitfalls To Watch Out For

There’s a commonality between those trying to gain weight and those trying to lose it in the comments they make when trying to succeed at either one. And that is they say they’re eating in a calorie surplus and they’re not gaining weight.

However, just like those who say they’re eating in a calorie deficit and not losing, they’re not. They just think they are for one reason or another.

A calorie deficit means you lose weight, and a calorie surplus means you gain it. If you’re not gaining, then you’re not in a surplus. It really is as simple as that.

And it honestly doesn’t matter what some app or wearable told you. The app/wearable is wrong if you’re not gaining, or the values that you input are. Probably both.

Here is what to do: count your calories, and whatever those calories are, add 250–500 to it and continue to monitor and weigh yourself. If you’re still not gaining, add another 250–500 and repeat.

You might surprise yourself as to how many calories you can add to your ‘maintenance value’ before the scale starts moving. I can add about 1000 calories, but I know people who can add even more than this.

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Anyway, ignoring this common pitfall of thinking you’re in a surplus when you’re not, there’s five other pitfalls to watch out for that can make progress non-existent, or at least fraught with difficulty:

Lack of consistency.

Too much protein.

Too much fibre.

Too much liquid.

Too little fat.

​Lack Of Consistency

This is the main one here. Consistency is fundamental. Every day you want to be in that slight calorie surplus. It’s no good overeating Mon–Fri and then chronically under eating on the weekend. The result could be that nothing changes and you just end up spinning your wheels for months on end.

The same can be said with routinely skipping meals. Not eating until midday, or skipping lunch, etc., can play havoc with trying to put on weight, especially if you lack sufficient appetite to put those missing calories back in when you do finally eat.

Be diligent with your surplus. Keep a journal if need be.

​Too Much Protein

How much protein you want to eat will depend on if you’re trying to gain muscle or just put on weight.

For building muscle you likely need to eat more protein than maintenance, but 2g/kg of lean mass is probably more than enough for most people, but protein is very satiating so don’t go overboard on it—it may just fill you up too much that you can’t get the necessary calories down to gain weight.

For just gaining weight, a high protein diet could leave you too full and satiated to get in needed calories, and half the amount listed above for building muscle is likely enough.

Of course, some protein sources, such as fatty red meat, are already high in calories, so they’re win/win.

​Too Much Fibre

The same type of argument for protein applies here with fibre also—it’s very satiating per calorie.

Of course, this isn’t to say that you should forgo vegetables and fruit. You shouldn’t. Continue to eat vegetables and fruit, just don’t eat so much of it that you’re totally stuffed on hardly any calories.

High fibre diets are excellent for losing weight for precisely this reason.

​Too Much Liquid

Careful with drinking a lot of liquid before or during your meals. The liquid can bloat you out, especially if it’s carbonated. The result could be you end up hardly eating anything.

​Too Little Fat

Fat, like sugar, gets demonised, but there’s nothing inherently wrong with fat, and you do need to eat it.

Fat, as mentioned already, can be extremely helpful for trying to gain weight due to the high amount of calories in such little volume as well as making things taste a lot better.

Don’t shy away from fat, particularly unsaturated fats as they’re healthier in larger amounts.

Oils, like olive and flax, as well as high-fat foods, like salmon, nuts, seeds, etc., are good ideas.

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Now, once we’ve got ourselves on track and we’re reliably and consistently gaining weight, we want to be at least a little careful with what we’re doing because if we don’t steer the excess energy into healthy tissue we can end up just piling on a bunch of fat. And this, for various health reasons, is not a good idea unless we’re sorely lacking in it already.

And the way we steer the excess energy into healthy tissue is by steering it toward muscle growth. And we do this through resistance training.

Resistance Training

For the majority of people, it’s probably a good idea to take up some form of resistance training along with gaining weight because then some of the extra calories are going into new muscle growth. We’ll still likely gain some fat along the way, but it won’t be as much as if we didn’t train our muscles.

Many people can have an aversion to training their muscles, notably women, as they seem to think they’ll get some variation of ‘big and bulky’, and they don’t want that.

However, here’s a simple fact for you, you won’t. Even if you dedicated your entire life to muscle building for the next 10 hard years straight, the chance of you ending up ‘big and bulky’ is fleeting, at best. So don’t be scared about developing your muscles.

Hard training coupled to a healthy overall lifestyle generally leads to a ‘toned look’, not a big and bulky look. A full-body program done twice a week is an excellent place to begin.

There’s also no need to major in the minors with this stuff, at least not in the beginning. No need to worry about your ‘training split’, calculating your macros, weighing every gram of your food, etc. Way too many beginners worry about this stuff when all they really need to do is get under the bar and lift it on a consistent basis with high effort.

Training our muscles is an all-around healthy thing to do, so try and get on board with the idea—you’ll feel better, fitter, and be more physically adept and capable as a result.

Doing some form of exercise like this can also increase your appetite somewhat, and considering that a gym session doesn’t burn all that many calories, the chance of you overshooting them is pretty high, which is a good thing for gaining weight.

Cardio, surprisingly, can also be a good idea for some as it increases their appetite. But this is not the case with everyone as it’s very much an individual and subjective thing, so don’t go doing a lot of cardio if it doesn’t because it’s just burning energy that you’re already struggling to get enough of.

​How Long Does It Take To Gain Weight?

This seems to be a common enough question that it’s worth including it before we close with some example foods, but the answer to it entirely depends on the size of your surplus, in exactly the same way that the rate at which you lose it entirely depends on the size of your deficit.

However, roughly 500g/1lB per week would probably be a good rate to target for the majority of people since it’s not too fast if your focus is muscle building and not too slow if your focus is simply weight gain.

This rate of weight gain can be achieved with a surplus of roughly 500 calories per day.

If this seems slow then you might want to just reign in your impatience a bit and set your time horizon a bit longer. At this rate, you gain 6kg/12lB in 3 months—which is actually a lot of weight in just a few short months.

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Let’s finish with some example foods.

​Example Foods

Ignoring the examples above under the headings Add Calories To Things, as well as Liquid Calories, both of which should go a long way in assisting you with getting more calories in, an internet search will likely throw up numerous examples of food choices you can try.

However, I thought I’d just conclude with a few simple examples of particular things I’ve used that have brought success.

​Peanut Butter and Honey Sandwich

This can pack quite a punch, a few to several hundred calories, depending on how much peanut butter you use. Add a banana for more goodness and taste.

A banana dressed with peanut butter is also a favourite of some.

Note that this is in addition to your meals, so eat a quarter to half at semi-regular intervals throughout the day.

And space them out so they don’t interfere with your appetite around meal times.

​Peanut Butter and Seeds In Porridge

This is actually a staple of mine because my breakfast is generally porridge and fruit, but adding peanut butter and seeds to it can easily add a couple of hundred calories.

Add some honey for even more calories.


A ‘healthy cereal’ is probably best here, but nearly all of them are fortified these days with a whole bunch of stuff, so virtually none of them could be considered ‘a bad choice’.

Granola is a good example because, once again, it has nuts in it, which are high calorie.

Make with full-fat milk for even more calories.

​Trail Mixes

Trail mixes of nuts and dried fruit pack quite the punch. Use them for snacking.


Hundreds of calories a day can be added with condiments alone, so find ones you like and add to taste.


Gaining weight is the result of consistently eating in a calorie surplus. The surplus should be large enough that you’re reliably gaining weight.

The route chosen for the calorie surplus should ideally come from high nutritional sources, like whole foods, but some people will require things like liquid calories and higher calorie-dense food simply by stint of their appetite not being high enough.

Some form of concurrent resistance training is a good idea since it will lead to weight gain without excessive fat gain.

It’s worth repeating again that the foundation upon which all this is built is consistency. Chronically undereating for a day or two every week can easily undo all the surplus you were achieving on the other days.

A good place to begin is by counting the calories you’re currently eating, then go from there.

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