The feeling of tiredness and drowsiness that one feels after eating is a physiological phenomenon called "alkaline tide", better known as "pig's disease".
The alkaline tide is a low energy, product of the activity of the parasympathetic nervous system (SNP), caused by an excess in the production of bicarbonate in the blood.
The main cause is the excessive intake of food, mainly fat. (Increases the production of hydrochloric acid, so more blood goes to the digestive process)
When ingesting food, the stomach produces hydrochloric acid which, in turn, needs the production of bicarbonate to compensate for it. To produce bicarbonate, blood electrolytes are exchanged into the cells of the stomach. Blood is subtracted from other organs, such as the brain, and this increases the sensation of sleep. This sensation usually lasts from 5 minutes to two hours.
What to do to avoid it:
1. Eat a low-fat diet.
2. Greater consumption of vegetables
3. Eat little and slowly
4. Eat 3 to 5 times a day.
5. Walk 10 to 15 minutes after eating.
6. Drink plenty of water.
7. Sunning (generates vitamin D that reduces the production of melatonin, the hormone that produces sleep).