In the case of women, extra weight may appear because of the fluctuations of the reproductive hormones that show up during pregnancy and menopause .Women are more likely to store more fat than men, because women present a lower basal fat oxidation indicator compared to men. Researchers believe that basal fat oxidation is connected to the loss of fat-free mass for aging women.

Some of the substances that may increase the risk of developing obesity are serotonin, insulin, and leptin. These substances may influence in different ways how men and women are predisposed to gaining weight.

Serotonin, a substance that regulates body temperature, mood, anger, sleep, sexuality, aggression, and appetite, is strongly related to the body mass index (BMI). When the BMI increases, the level of serotonin decreases. When it comes to weight loss, the difference between men and women is the BMI level that triggers the decrease of serotonin. For women, the amount of serotonin decreases when they reach a BMI that classifies them as "obese", while for men this happens when their BMI shows they are "overweight". To read the rest of this article, go to , an online weight loss community featuring calorie counter, carbs counter, BMI calculator, diet planner, workout planner and other weight loss tools.

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Leptin is a product of fat cells and has a role in regulating the energy expenditure and appetite. Leptin levels are higher for women than men at any BMI level. Men may have

lower levels of leptin if they have a higher level of testosterone. Specialists believe that leptin levels may influence the body weight starting at puberty. The difference in leptin levels occurs in boys who have a high level of testosterone and girls with higher fat mass.

Pregnancy can also affect leptin levels. The amounts of leptin is higher in women who are pregnant with female fetuses, but not for those pregnant with male fetuses.