Most people associate middle-age weight gain with poor diet, inactivity, and slowed metabolism. But one reason so many weight loss programs ultimately fail is that they don’t address the impact of hormones on weight gain – particularly as people age. Here’s a quick breakdown of how imbalances among different hormones commonly affect weight gain:

Estrogen deficiency interferes with appetite control and calorie burn. It’s a major factor in determining body fat distrubution – primarily in lower abdomen and thighs, although after menopause women tend to develop abdominal fat similar to men.

Testosterone is involved in maintenance of lean body mass, bone density, sex drive, skin elasticity and cardio vascular health in both sexes. A testosterone deficiency results in a loss of muscle, decreased metabolic rate and subsequent fat build-up. Testosterone level decreases with age, leading not only to fat weight gain and loss of muscle strength, but increased risk of heart disease, depression, and diminished sex drive.

Thyroid hormone affects virtually every bodily function, including regulating metabolic rate, energy level, and heart production. An under-active thyroid encourages fat weight gain while making it difficult to shed weight (despite diet and exercise). Estrogen and testosterone imbalance, in turn, may inhibit thyroid function.

People with high cortisol levels characteristically put on visceral (abdominal) fat and have a hard time losing weight. Excess cortisol generated by chronic stress is also the most commonly reported trigger of binge eating. Excessive insulin, meanwhile, promotes fat storage and over-production of cortisol, which is one reason why it’s so important to determine blood sugar and insulin levels as a part of a weight management program for obese individuals.