Heard at the gym: theories about diet

Fitness club is not only the place where you work out. It is also the place where you exchange thoughts and opinions, and give advice that is sometimes unjustified. Of course, an important part of conversations are the issues concerning training, supplementation and diet. Unfortunately, significant part of the presented statements seem to origin from anecdotes and do not refer to reality, which is not a problem for many people to use them with respect and seriousness. In this article I will cite and comment on the strangest theories I have heard in fitness clubs.

You can eat fruit only till noon

The theory, which assumes eating fruit until noon does not derive directly from the fitness world, but, for some reason, it has stayed there. The followers of such rule are not only laics, but also doctors, trainers and dietitians. The recommendation concerning limiting the intake of fruit to the first half of the day is justified in two ways. First of all, the enthusiasts of such advice refer to quite popular belief, that high-carb products with “high glycemic index” are better to be eaten in the morning, alternatively till noon, in order to give the body the chance to burn the supplied energy (according to such belief, there won't be such possibility in the evening). Second of all, there are also more sophisticated arguments refering to the “daily activity of the enzymes”, which take part in decomposing the eaten food and which may decompose fruit efficiently only till noon.

Do such explanations make sense? Of course, not!

In practice, there is no convincing proof that consuming highly-glycemic and more carbohydrate products in the first half of the day is better for health and shape than tranferring them to later hours. Instead of that, there are results of studies, which confirm, that eating carbohydrates before sleep may support body fat reduction! Besides, fruit does not belong to the group of highly-carbohydrate products! They contain about 8-15% of saccharides! If it comes to the theory, which refers to the activity of digestive enzymes, it also belongs to science-fiction. Excreting digestion enzymes does not depend on the part of the day, but on consuming food. There are no professional sources, on the basis of which one could conclude, that, e.g. at 7.30 p.m. or 9.45 p.m. the body does not produce any enzymes enabling the decomposition of fruit (i.e. mainly disaccharides, such as saccharose, which is decomposed very efficiently and fast).

You have to complete glycogen after workout as fast as possible

Despite writing about this matter many times, large part of people who come to fitness clubs believe that consuming carbohydrates after workout is a priority, because it realises the necessity of completing the lost muscle glycogen. The followers of such solution repeat, that “it is like this, because it always has been”, and they sometimes refer to the results of scientific studies! Those studies, or rather one research, indicated that in the after-workout period, the tempo of glycogen resynthesis is much faster than in other parts of the day. Therefore, there's simple conclusion, that this fact is worth using in pracitce, because if you don't, you will lose the physiological “bonus” making it possible to improve effort abilities and increase the tempo of protein synthesis. Unfortunately, such interpretation is far-fetched, because:

  • completing muscle glycogen is not a priority after resistance training, most of all, because its loss doesn't have to be significant (gym workout is not a marathon...),

  • even if completing glycogen was a priority, you should hurry to complete it only if the next workout was withing the next few hours. If the break between workouts is 24 hours and longer, the only matter you have to take care about is the total supply of carbohydrates during this time (it should be high enough – if it's not, you will be unable to fully complete glycogen). This fact is confirmed by scientific studies,

  • completing glycogen is not essential to stop catabolism, or to start the process of muscle protein synthesis, as these are the priorities after resistance training (catabolism blocks the increase of insulin, which occurs after consuming carbohydrates),

  • To sum up: there's no necessity of completing glycogen right after resistance training, which does not mean that you should avoid consuming carbohydrates in that time. It's opposite, their presence helps to achieve proper hormonal response from the body and supply energy required to enpower the tracks of protein synthesis. However, it doeasn't have to be large amount of simple sugar coming from glucose, or any type of carbs or vitargo drinks. Unless you have another workout within the next 24 hours.

More than 30g of protein will not be absorbed from one meal

“Bio-availability of protein” is a really nice topic for various speculations. One of the popular theories states that there is some limit of possibilities for the body to use protein within one meal, which is about 30g. Comparing this belief with reality reveals its discards quite fast. If you assume that a well-nutritioned sportsman eats five meals a day, it will turn out that he consumes 150 g of protein per day (it will be the “bio-availability limit”). In case of an individual weighing 80kg it gives almost 1.9g per 1kg of body mass, which is the wanted amount in resistance and speed sports.

However, in case of a professional bodybuilder, who weighs 125 kg out of season, it gives only 1.2g of proteins per 1kg of body mass. According to the mentioned limit, such competitor will not absorb more when eating 5 meals a day. Whereas, it's good to know, that some of the former bodybuilders, such as Nubret Serge, used to eat only two big meals during 24 hours! According to the cited opinion, they would be able to use only 60g of protein during one day. Is it even possible?

Fortunately, if you want to answer the question mentioned above, you don't have to base only on speculations. There are studies, in which it was observed that even during eating very large amount of protein within one meal (reaching 70g), the body uses amino acids gained this way. What's interesting, if there is any threshold of using the supplied protein in the process of synthesis (but it's not strictly 30g, but individual), increasing the intake of protein above that limit causes stronger block of catabolism of the body's protein. As a result, the net balance of protein turnover improves. You can read more about that in the study linked below:


So, the belief, according to which the body is able to absorb only 30 g of protein from a meal turns out to be untrue.

By eating more often, you speed up metabolism

The idea of “frequent and small meals” in fitness clubs is often perceived as a common way of making the work on the body easier, or even necessary, if you want to “speed up metabolism”. What's interesting, also trainers, or even dietitians, believe such statements and copy this story to others. Indeed, the idea seems reasonable. After all, there is something like the “after-meal thermogenesis”, thanks to which during and after the meal metabolism increases and there is increased burning of the energy substrates (which is connected, among others, with digesting food, but also with absorption and metabolism of the supplied components). If it is like that, the more often you eat, the more often you increase the expenditure, which may cause the belief that high frequency of meals leads to larger energy expenditure.

Well, such thinking is misleading. Because the thing that matters is what and how much we eat during 24 hours.

If you eat rarely, you also speed up your metabolism between meals more rarely, but the effect of after-meal thermogenesis is stronger in time. If you eat more frequently, you also raise the tempo of metabolism more often, but single meals are of less importance. In both cases you will burn the same amount of energy. Of course, this happens in a situation when the daily supply of food is identical in both cases. It's worth knowing, that in 1997 French scientists did an analysis of the available results of studies, which confirmed that there is no convincing proof for higher frequency of eating meals to speed up metabolism in any way, or – which is particularly interesting – that it makes it easier to lose weight. You can read more about it in the publication linked below:


You have to “cut down on carbs” to burn fat

First, I have to praise the revolution, which happened in the way of thinking of the fitness clubs' users. Nowadays there aren't many who think that you have to “lean” your daily diet in order to lower the amount of body fat. People finally realised that low-fat diet doesn't have to be the only proper way of improving body composition. Unfortunately, in the place of one stereotype there is another one. Now, majority of people, who want to get rid of excess amount of centimetres and kilograms, believe that they should limit carbohydrates to minimum to reduce body fat.

Of course, there's no doubt that introducing carbohydrate restrictions may be an efficient way of increasing the reduction of body fat. However, some controversies concern the safety of using solutions of such type, although, during the last two decades there have appeared many studies indicating that well-balanced low-carb diets are fully safe for health, they can even cause many advantages. But it doesn't mean that low-carb diet is the only right way of improving body composition! It is one of the possible solutions and you shoulnd't be so dramatic about it. I described this matter in the following articles:

Is “cutting on carbs” necessary during body fat reduction? Part I

Is “cutting on carbs” necessary during body fat reduction? Part II

I will continue this topic in the third part of that article, so I encourage you to follow the articles, which appear at Afterworkout.com.


The theories mentioned in this article show how many common beliefs are hidden behind the doors of fitness clubs, and also how the untrue information has dominated the knowledge about diet aimed at improving body composition. Of course, you can find here only some examples, of which there are much more, but it would be still difficult to gather them all, or even the more recent ones. The point is, that when completing knowledge about nutrition, you shouldn't trust too much the things you hear at the gym, because if you stay with only true information, it would turn out that it's surprisingly quiet at the gym...