A very interesting study on postpartum weight has just come out, and despite the reference model being mice, the results are in line with what was already assumed with the weight gain after pregnancy that some women experience a few months after giving birth. .

In fact, although with breastfeeding there is a greater expenditure of energy ( I speak precisely here ), not all women are able to lose weight after childbirth.
Indeed, in some cases they even gain weight, usually after the first three months.

But what is it due to?
Scientists at  UC San Diego School of Medicine used pregnant female mice to find out. They already subjected them to two distinct diets during the period of pregnancy. The first diet was a balanced diet , while the second group’s diet was higher in fat.
Results: Although both groups of mice lost weight soon after the mice were born, the group that gained more fat during pregnancy strangely gained weight after about three months of pregnancy .

This was despite the fact that the post-pregnancy diet was the same as in the first group.
Also, this weight gain, and more specifically body fat, is long-term.

Apparently, the fat in the pregnancy diet would cause an epigenetic metabolic shift .
By permanently changing the hormonal profile of those who give birth. On the one hand, there would be an accumulation of both visceral fat and subcutaneous fat. On the other hand, it seems that the metabolism is also lowered, reducing the calories burned.

Therefore, the advice is to eat a less high-fat diet during the gestational period.

Insights: 
Diet in pregnancy. How much and what to eat. 
The mini guide to exercises and diet in pregnancy.