Dear Doctor,

1. My housemates and I practically have the same type of meals daily. Unlike them, I even create time to exercise at least twice every week. However, they are more slender and their tummies are smaller than mine. Why is this the case yet we eat the same food and they lead a more sedentary lifestyle than me?

Achilles

Dear Achilles,

You have raised a very interesting question which bothers many people around the world. Central obesity or increase in tummy girth usually occurs due to imbalance between calories consumed and burnt. That is excess consumption of calories (more than what the body can metabolise) and or lack of exercise. Apart from this there are several factors that determine central obesity. Apart from the food taken, drinking sweetened beverages or alcohol, also adds on the total calories consumed. Obesity has also been linked to excess meat consumption.

Some foods like beans, peas, bran or dates contain phytoestrogens (substance that mimic natural estrogens).

Excess consumption of such foods may cause central obesity. Endocrine disorders such as cushing’s syndrome and hypothyroidism can also cause central obesity. Medicines like corticoids taken over some time cause obesity as adverse effects. Genetic factors also play a role in determining body build and obesity. This partly explains the variation seen in body weight in individuals with same life style factors. Also if a pregnant mother is obese, the baby born can be programmed to become obese when grown up.

Interestingly, one may apparently look obese, but may not be so actually because body weight varies as per height, weight and bone density of a person. Therefore one is considered to be obese only when BMI (body mass index-a ratio of weight to height) is more than 25. Regarding central obesity, waist-hip circumference more than 0.90 in men and .0.85 in women is considered significant.

Whatever the cause of increased tummy girth, it is a risk factor for diabetes, high blood pressure, heart problems, asthma and some cancers as well. Hence it should be checked and reduced by a low calorie diet and regular exercise. There is a myth that spot exercises burn fat of that area (like sit-ups for increased abdominal fat). But this is not true. Sit ups can help build muscles but will not affect abdominal fat in any way.

Dr Rachna Pande  is a specialist in internal medicine at Ruhengeri Hospital