Q: My friend's 89-year-old father has been obese all his life and his diet is awful. But his blood sugar is normal, and his total cholesterol is 122. And his doctor tells him he has the heart of a 30-year-old. How is that possible?
A: The new term for this condition is metabolically healthy obesity.
diabetes and heart disease that is no greater than someone of normal body weight. In fact, the risk may actually be lower.
Obesity is defined as a body mass index (BMI) of 30 or higher. BMI is a number that's based on the relationship between weight and height.
The reason that this subgroup of obese people doesn't have the same diabetes and heart disease risk is almost certainly genetic. Scientists have yet to discover which genes control it.
But we do know a lot about the profile of the metabolically healthy obese:
Despite their weight, they tend to have smaller waist sizes than most obese people. A large waist means you carry more belly fat. Doctors call it visceral fat. More belly fat translates to a greater diabetes and heart disease risk.
Their body cells have normal insulin sensitivity. This means the cells use insulin in a normal way to turn the glucose (sugar) in food into energy. Most obese people develop insulin resistance, when cells don't use insulin well. Insulin resistance is the first step toward type 2 diabetes.
They tend to have lower total cholesterol levels and normal blood pressure.
They don't show evidence of lasting, low-level inflammation, which is common in metabolically un-healthy obese people. Long-term inflammation is linked with an increase in heart disease and stroke risk. A study published earlier this week confirmed the lower levels of inflammation in people who are obese but metabolically healthy.
Metabolic health matters a lot, no matter how many pounds show up on your scale. You can improve your metabolic health even if you didn't inherit those "good genes" by following these tips:
1. Stay physically active as much as possible during the day.
2. Dedicate at least 30 minutes per day to exercise. Ideally, aim for 60 minutes each day.
3. Eat a Mediterranean-style diet.
4. Load up on fruits, vegetables and whole-grain foods.
5. Eat healthy sources of protein, such as fish, nuts and beans.
6. Avoid tobacco products.
(Howard LeWine, M.D., is a practicing internist at Brigham and Women's Hospital, Boston, Mass., and Chief Medical Editor of Internet Publishing at Harvard Health Publications, Harvard Medical School.)
(For additional consumer health information, please visit http://www.health.harvard.edu.)