If we compare, in terms of obesity, body silhouettes, “pears are healthier than apples”, concludes this study from University of California – Riverside. Data that is addressed here more specifically to each sex: because in women, fat generally accumulates around the hips, giving a pear-shaped silhouette, in men, fat tends to accumulate around abdomen, creating an apple shape. This study presented in the journal Frontiers in Immunology and conducted on mice, concludes that it is healthier to “be” a pear than an apple.
Previous animal studies have shown that females are protected against weight gain when they are young, due to the high presence of estrogen in the ovaries. This finding has led to a better understanding of the risk of weight gain after menopause. This new research, also conducted in mice, finds that after a high-fat diet, male mice show low testosterone levels and decreased sperm count – in addition to neuroinflammation in the brain, not seen in female mice. The team therefore looked at the role of hormones in weight gain and obesity.
Obesity, hormones in males: male mice on a high-fat diet,
- develop, like men, a metabolic syndrome (see visual) including type 2 diabetes, insensitivity to insulin and markers of vascular disorders;
- store fat deeper (visceral and abdominal fat) which can affect internal organs. Their silhouette is more like the shape of an apple. The accumulated fat then recruits immune cells from the bloodstream which are activated, leading to inflammation. Peripheral immune cells, including macrophages in particular, cross the blood-brain barrier and this infiltration of peripheral immune cells into the brain induces neuroinflammation;
- show an almost 50% reduction in their testosterone and sperm levels.
Obesity, hormones in females: female mice on a high-fat diet,
- store fat differently than their male counterparts, rather subcutaneously, just under the skin;
- their estrogen hormones seem to protect them to some degree from fat accumulation;
- they show neither neuroinflammation nor changes in reproductive hormones, suggesting that they are protected by factors other than ovarian estrogen.
The message is therefore aimed at both men and women: “ Watch your diet and keep an eye on your weight and in particular on the accumulation of abdominal fat ”.