The feeling of hunger is nothing pleasant. However, does it mean that when we can hear our stomach growling or when we feel like having something to eat, the catabolic processes start within the muscle tissue? In the fitness world such belief is very common. But is it true?
Hunger yesterday and nowadays
The feeling of hunger has accompanied us ever since the dawn of time. Actually, you could say that present is special in this matter. From the evolution point of view, the situation when we can constantly avoid the feeling of discomfort caused by lack of food, is something totally new. Supermarkets, convenience stores, home fridges are all filled with food in advance – such situation is not natural. In nature, you have to procure food. It's worth reminding, because nowadays, the feeling of hunger is perceived as something very dangerous in the bodybuilding world for the body composition and metabolism. Supposedly, even temporary hunger causes the loss of hardly gained muscles and slows down metabolism. It's good to compare such beliefs with facts.
Where does the feeling of hunger come from?
During evolution, human body has developed quite complicated mechanisms, which let it control hunger. When they work properly, it's possible to cover the demand of the body for:
What's important, it happens with quite small risk of excessive fattening. The whole process is regulated by many hormones and neuropeptides. Thanks to that, it's possible to regulate the state of hunger and satiety depending on the level of glucose, amino acids and lipids in blood, as well as on the level of filling the stomach, the level of gathered energy supplies and other aspects. The problem is that not only neuropeptides and hormones take part in the regulation of food intake, but also various external circumstances, such as: cultural or social aspects and emotions.
But that's not all!
Also the properties of the food itself are very important – its temperature, appearance, smell and taste, as well as the presence of particular components. In case of consuming some food products, we feel hungry much earlier than after eating other types of food, despite similar calorific content. Fine, you know the biological justification of hunger and that the regulation of hunger is very complicated. But still, there is the matter of the metabolic consequences of the feeling of hunger, most of all, its influence on muscles.
Hunger vs the “energetic status” of the body
Hunger is the state, which may inform that the body is probably struggling with low level of available energy coming from food. It may be this way, but it doesn't have to! In some situations, the mechanisms of appetite control are disregulated and the body reacts “over the top”. It may happen after long-lasting aggressive period of slimming. We sometimes mistake hunger with appetite ourselves. Whereas, “the appetite for...” may appear despite lack of the feeling of hunger, and even in a situation of being full. That's why after a filling dinner we have problem to resign from a piece of cake.
Knowing all that, you should take under consideration the fact that the feeling of hunger doesn't have to be connected with “the lack of energy supply” by the body. Even if it was like that, it wouldn't have to be connected with muscle catabolism, because in the calorific deficit state, the body may reach to glycogen and lipid reserves!
Hunger and catabolism
It's good to wonder about the conditions, which have to be fulfilled for the feeling of hunger to be strictly connected with muscle catabolism. Well, such dependency would be supported with the fact, if the areas of hunger and satiety placed in hypothalamus reacted only on the biochemical changes from the muscle tissue. For example – those could be the changes caused by stimulating the catabolic enzymes. Another option is that stimulation of the hunger area in the hypothalamus would result in mobilization of the proteolytic enzymes in muscles, which would cause stronger catabolism. However, in practice, nothing like this happens. It's easy to visualise this fact by mentioning that the feeling of hunger, along with growling of the stomach are sometimes noticed under the influence of some smell or even look of your favourite dish.
But, the fact that we are getting hungry when smelling grilled neck or fried steak means that the muscle catabolism is stronger at that moment? Well... it would be curious. It would mean, that the smell of food may be catabolic...
It's also worth reminding, that in some cases the neuroendocrine mechanisms, which regulate appetite, are disturbed. The factor, which is responsible for that is either excess amount of fatty tissue in the body (causing leptin resistance), or wrong diet, which may also fosters leptin resistance. As a result, we can feel hunger also when the energy reserves are full and the muscles have access to amino acids. Additionally, we tend to exaggerate the discomfort connected with this feeling.
When hunger appears, it may have nothing in common with muscle catabolism. Such state is sometimes the result of many factors, including cultural and emotional. Hunger may be also connected with the exposure to the smell of tasty dishes. It may be also mistaken with appetite. It should be accepted that worrying too much with temporary hunger and panicking when one meal is omitted are more dangerous for the muscles than the momentary lack of supply of the nutrients.