Several medical doctors over the years have told me that, though it is unhealthy to be very overweight or obese, it is a good idea to be a little overweight (i.e., on the high end of the healthy BMI range for your height), because if you ever become very sick and can’t eat for a week or two, your body will survive on whatever fat and muscle mass you have. They have also told me that being very thin can worsen osteoporosis, because it takes more bone strength to resist the pull of gravity on a heavier body, and the body automatically adjusts for this.
After having once asked a nutritionist and done my own research about how to healthfully maintain enough weight, here are the conclusions I reached:
- Protein hurts the heart the least, is easiest to burn off through exercise, and low-fat protein (e.g., from lean meats like chicken and fish, nuts, beans, etc.) is healthiest for the heart and arteries.
- The body needs a certain amount of fat, and unsaturated fat (e.g., from nuts, vegetable oils, soy milk, etc.) is usually healthier than saturated fat (e.g., from dairy, beef, or pork).
- In order to gain or maintain weight, one must have a surplus of calories. It’s usually easier to eat a lot, if one eats slowly or frequently, though this can be hard on the teeth.