I was under the impression that carrying extra weight can lead to diabetes because the fat tissues have adverse effect on insulin efficiency, or something like that. Diabetes runs heavily in my family and my doctors have always said that carrying extra weight makes a big difference. Do you know anything about that?

There is a relationship between weight and obesity, and you are correct about increased fat tissue decreasing insulin sensitivity. The vast majority of people diagnosed with Type 2 diabetes are overweight. However, being overweight does not automatically mean you will develop Type 2 diabetes, just as being thin does not automatically prevent you from developing Type 2 diabetes. Many things influence this, including family history, diet, and exercise. 

Again, while there are certainly relationships between weight and health, it is not a guarantee that a person who is overweight is unhealthy. Half of people who are overweight and a third of people who are obese are healthy. If the concern is health, then let’s focus on true indicators of health: what we eat and what we do, not what we weigh.