Weight gainers: When to use them and when not to, by Roberto Castellano

Gainers have a bad reputation. And, as is often the case in sports nutrition, not because they are inherently bad, but because they have been used poorly, recommended even worse, and sold as the universal solution for people who did not need them. The problem is trying to sell as magical something that is nothing more than convenient food, but this simple thing may be the only way out for many people who need an enormous calorie intake to grow.

For years, they have been associated with products loaded with sugar, unnecessary insulin spikes, and absurd fat gains, because they used to be made in a way that made them little more than expensive Nesquik. All of that does exist, yes. But reducing the concept of a gainer to that caricature means failing to understand what they are actually for.

A gainer is nothing more and nothing less than a calorie tool. A way to consume calories, carbohydrates, and protein in liquid, concentrated, and easy-to-consume form. And when you understand it that way, it stops being a “beginner” supplement and becomes something very useful in specific contexts, whether you are a beginner or not, whether you are a bodybuilder or a cyclist. The problem is not the gainer; the problem is thinking that everyone needs one—or that no one should use one.

Let’s put things in order.

THE REAL PROBLEM: NOT EVERYONE CAN EAT WHAT THEY NEED

There is a reality that many people overlook when they talk about “perfect” diets: not everyone can eat enough solid food to meet their calorie needs. And I am not talking only about a lack of discipline. I am talking about people with low appetites, slow digestion, high stress levels, physically demanding jobs, chaotic schedules, or simply limited stomach capacity.

For someone who needs 3,500, 4,000, or even more calories a day to gain weight or muscle mass, basing everything on solid food can become a full-time job. Eating stops being something functional and becomes a constant source of stress. And when food feels like a burdensome obligation, adherence goes out the window.

This is where gainers start to make sense. Consuming calories in liquid form is metabolically easier, requires less digestive effort, less time, and less psychological strain. Facing another plate of rice and meat when you are already full is not the same as drinking a dense shake and getting on with your day.

Liquid calories and digestion: less stress, better adherence.

From a physiological standpoint, liquids leave the stomach faster than solids. This reduces the feeling of prolonged fullness, facilitates digestion, and allows calorie intake to be distributed more effectively throughout the day. When the total volume of food is high, this is a huge advantage.

Moreover, in very high-calorie diets, the digestive system is often one of the first to suffer. Heaviness, bloating, gas, lack of appetite… all of this is not only uncomfortable, but ultimately compromises the quality of the diet. Introducing some of those calories in liquid form reduces the mechanical and functional load on the digestive system, allowing the rest of the solid meals to be better tolerated.

Therefore, far from being a bad idea, using a well-formulated gainer can be a smart decision when the goal is to increase or maintain a high calorie intake without wreaking havoc on digestion.

WHAT A WELL-FORMULATED GAINER REALLY IS

A good gainer is not sugar with protein. A good gainer should be based on:

• A source of easily digestible carbohydrates,
• A sufficient amount of high-quality protein,
• A coherent ratio between the two according to the goal,
• Reasonable digestibility.

Modern formulas often use carbohydrate blends such as oat flour, maltodextrin, cyclic dextrins, or similar ingredients, combined with whey protein. The key is not so much the specific ingredient, but how well it is tolerated and how it fits into the overall dietary context. If, for example, it is for after training, it could indeed be based on simple carbohydrates and fast-digesting proteins, but if we want to use it as a meal replacement, ideally it should contain fats (this is easy to achieve by adding coconut oil or extra virgin olive oil) and sequentially absorbed carbohydrates, in addition to protein.

One thing should be made clear here: a gainer does not replace meals per se. It supplements calories. It is a tool for adding to your intake, not for replacing all solid food. When used systematically as a substitute for solid meals, problems arise.

WHO IT MAKES SENSE TO USE A GAINER

There are clear profiles for whom a gainer can be especially useful.

• People with a high metabolism and little appetite who eat well but do not reach the calories needed to gain weight. Here, a gainer is not a shortcut, but a practical solution.
• People with demanding training schedules who need a lot of calories and do not want to spend the whole day eating. Introducing a high-calorie shake between meals or after training makes day-to-day life much easier.
• People looking for a more relaxed diet, without constantly weighing food or forcing themselves to eat when they are not hungry. A gainer reduces friction.
• People in phases where the goal is to maintain body weight or muscle mass with a high-calorie intake, but with little mental bandwidth for nutrition, such as during periods of work stress, travel, or major life changes.

WHEN IT DOES NOT MAKE SENSE TO USE A GAINER

It also has to be said: not everyone needs one.

If you can easily reach your calorie target with solid food, digest well, and enjoy eating, a gainer offers nothing special. It also makes no sense for people with a clear tendency to gain fat easily if the calorie context is not properly controlled.

The problem arises when a gainer is used as an excuse not to learn how to eat, or when it is introduced without control into diets that are already high in calories. In those cases, the gainer is not responsible for the increase in body fat; it is poorly managed excess energy.

THE ROLE OF THE GAINER IN A WELL-PLANNED HIGH-CALORIE DIET

The smartest way to use a gainer is as a calorie wildcard. Daily needs and circumstances are not always the same. There are days when you train more, move more, or simply eat less for whatever reason. That is where a gainer fits perfectly.

For example, adding a 500–700 kcal post-workout shake can make the difference between falling short and meeting your daily goal. Or use it between meals when you know you will not be hungry enough by dinner.

It can also be useful during phases when you need a lot of calories but do not want them all to come from solid food, avoiding that constant feeling of heaviness that eventually takes its toll.

Can you make “natural” gainers? Yes, and it is actually a good idea.

This brings us to a very interesting practical aspect. A gainer is essentially a combination of carbohydrates, protein, and, if you want to fine-tune it, some fat. And it can easily be replicated at home.

A simple, effective, and very well-tolerated version could be:

• water (or a plant-based drink if preferred),
• oat flour (a source of complex carbohydrates and soluble fiber),
• whey protein,
• extra-virgin olive oil, coconut oil, or blend it with peanut butter.

This combination has several advantages. Oats provide slow-release carbohydrates, whey ensures a complete amino acid profile with rapid absorption, and olive oil adds high-energy-density calories without increasing the shake’s volume. In addition, olive oil is well tolerated and offers clear metabolic benefits.

The result is a calorie-dense, easy-to-digest shake with no unnecessary added sugars and fully adjustable quantities. You can make it more or less caloric depending on the time of day or your needs.

GAINERS, INSULIN, AND UNNECESSARY FEARS

Another point that often sparks debate is the insulin response. Yes, gainers raise insulin levels. Like any meal containing carbohydrates. Demonizing this means failing to understand basic physiology. Insulin is not the enemy; it’s a tool for storage and anabolism. The problem isn’t that it rises, but when, how much, and in what context.

In active people who do strength training and have high energy expenditure, a post-workout insulin response is not only not negative, but may also promote glycogen replenishment and recovery. Fear of insulin often comes from extrapolating the metabolic problems of sedentary people to sports contexts where they do not apply in the same way.

THE FINAL KEY: THE GAINER IS NOT THE PLAN OR THE MIRACLE; IT’S PART OF THE PLAN OR A TOOL

A gainer won’t make you gain muscle mass if the rest of your diet and training are poorly planned. But it isn’t the villain some people want to make it out to be, either. It’s a useful, practical tool that, when used properly, is highly effective.

If you struggle to eat enough, need a lot of calories, want to simplify your diet, or reduce digestive stress, using liquid calories makes perfect sense. Whether with a well-formulated commercial product or a thoughtfully prepared homemade version.

The mistake isn’t using a gainer. The mistake is using it without understanding why you’re using it.

And as always, if you’re not sure when to introduce it, how many calories you should add, or how to fit it in without going overboard or falling short, it’s better to ask for help than improvise. Because in sports nutrition, as in training, doing simple things well always beats doing complicated things poorly.

And if you can’t find a combination on the market that’s exactly what you’re looking for, make your own with separate products. In the Moremuscle range, you’ll be able to find them all without any problem. In fact, if you think about it, it works out much cheaper than regular food—but remember, it doesn’t replace it; it complements it.

And as for the myth that they’re a waste of money, that would be like saying eating is a waste of money.