The directive to eat protein in the evening and carbohydrates during the day – especially in the morning – has spread more and more in recent years and is taken for granted today. The underlying physiological mechanisms are also scientifically proven and can be read in every physiology book. Here a very simplified and short summary, why this is so.
The 3 nutrients
The three nutrients fulfil manifold functions. At this point only the relevant main function is listed (more about the functions later in this article).
- The assumption is that our organism is active during the day and regenerates at night when we sleep.
- Therefore it is generally recommended to eat more carbohydrates in the morning in order to supply the body with enough energy.
- in the evening, on the other hand, carbohydrates should be avoided to a large extent and protein eaten instead. The following reasons are postulated:
- The body regenerates during sleep and therefore needs more protein (as “building and repair material”).
- In the resting phase, the body generally needs fewer carbohydrates.
- The intake of carbohydrates increases the insulin level. This, in turn, inhibits fat burning.
What’s the point of the slogan “slim in your sleep”? Admittedly, the proportion of fat burning is highest during sleep (up to approx. 75% of the total energy requirement). However, the total energy requirement of the body while sleeping is ridiculously low (a person with 100 kg of weight consumes approx. 90 calories (see The Compendium of Physical Activities Tracking Guide by Barbara E. Ainsworth). Then you will probably lose less weight ;-).
The calorie balance
Calorie balance means to weigh up absorbed and burnt calories against each other.
- If the calorie intake is greater than that of the burned calories, this is referred to as a “positive calorie balance”. This results in weight gain.
- If the calorie intake is smaller than that of the burned calories, this is referred to as a “negative calorie balance”. This results in weight loss.
It is preferable for the balance sheet to be drawn up on a weekly basis. Thus a “slip-up” such as the extensive feasting at a party can still be ironed out.
In order to prevent a deficiency/malnutrition, not only the distribution of nutrients (carbohydrates, fat, protein), as well as the total energy requirements, must be taken into account. You must also pay attention to sufficient intake of the other food components.
Nutrient distribution according to DGE in percent according to grams
Here once again the nutrient distribution according to DGE in percent is shown in a table. How the daily calorie requirement can be calculated can be found in the article Calculate calorie requirement.
(main)task of carbohydrates and protein
Carbohydrates are nutrients and the largest component of human food. They supply the body with energy. Carbohydrates are present in so-called chains, which are split again and again and become shorter and shorter until they are finally available to the body as an energy supplier in the form of glucose.
A short-chain carbohydrate is thus quickly available to the body in the form of energy but is also quickly consumed. Various long-chain carbohydrates are available to the body with a time delay so that it always receives sufficient energy.
Protein is the universal building material of our organism. Required as building material for muscles, blood, enzymes, antibodies and much more. As collagens they form up to 1/3 of the total body protein as skin, connective tissue and bones (too much protein is metabolized to fat).
Insulin and glucagon, the two antagonists of blood sugar management
Both insulin and glucagon are produced in the Langerhans islands of the pancreas. These two enzymes have opposite effects (antagonists).
(Main)task of insulin
There, glucose is either stored in the form of glycogen or converted into energy (glycolysis / citric acid cycle). Insulin also inhibits lipolysis (fat breakdown) in fatty tissue.
(main)task of the glucagon
New synthesis of glucose (gluconeogenesis) from amino acids – the components of proteins. In other words, glucagon has a protein-degrading effect, which leads to an increase in urea in the blood.
This glucose obtained from protein can be converted back into glycogen and, when glycogen stores are full, into fat.
Which mechanisms are behind the rule carbohydrates in the morning and protein in the evening?
Carbohydrates for breakfast
Carbohydrates are the number 1 source of energy for our body. Just in the morning – so the general attitude – it makes sense to supply the body with energy. An intake of carbohydrates causes the insulin level to rise. This means that the carbohydrates are crushed and are available to the body as an energy source.
The crux of the matter is: Insulin also inhibits the breakdown of fat. That bites itself now of course. Because fat has to be broken down to lose weight. Exactly here lies the core of the poodle. Without physical activity in the form of sporty training it becomes very difficult to lose weight. Decisive is again the calorie balance!
In the article myth fat burning I explain the connections between burning carbohydrates and fats.
Protein for dinner
In the evening it is now cheaper to eat protein – according to the general attitude. In the evening, the organism hardly needs energy in the form of carbohydrates, as it only has a basic need for energy overnight and during sleep.
In addition, the organism regenerates itself during this time and all necessary “maintenance and repair work” can now be carried out undisturbed.
Balanced and moderate – the mixture makes it
A healthy and balanced diet naturally includes more than just the intake of the 3 nutrients protein, carbohydrates and fat depending on the time of day.
The Nutrition Circle according to DGE (German Nutrition Society)
- Fats and oils
- Cereals, cereal products, potatoes
- vegetables, salad
- Milk, dairy products
- Meat, sausage, fish, eggs
Not to mention regular sports training. Because alone with the rule “carbohydrates in the morning and protein in the evening” no weight reduction can take place.
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