Given that the majority of men are overweight, the issue of underweight doesn't receive much attention.

Being thin is not harmful to your health unless you're so thin (BMI less than 18.5) that you don't have the fat and nutrient reserves you need in case of illness or injury.

Even if your weight isn't low enough to be a health concern, you may desire to gain weight for your appearance. Let's face it... willowy thin is a more desirable look for women than men in our society.

You'll need to consume an additional 500 calories per day to gain 1 pound per week. Fat is the most concentrated source of calories (9 calories/gram compared to 4 calories/gram for carbohydrates and proteins). Although increasing fat in your diet is an easy way to consume more calories, it's important to choose the right fats to avoid health problems. Thin people are not immune to heart disease.

In general, you don't want to increase your consumption of saturated fats (high fat meats and dairy) or trans fats (fried foods and snack foods). Instead, unsaturated fats, such as olive and canola oils, nuts, seeds, avocados, and olives are good high-calorie choices. You might munch a handful of nuts for a mid-morning snack, add avocado to your lunchtime sandwich, and drizzle some extra olive oil on your salad or pasta at dinner.

Low fat proteins, such as lean meats, poultry and fish, and low-fat milk and dairy products are good choices. Fruit juices contain important nutrients and are less filling than whole fruit, because the fiber has been removed. If you feel full quickly, consider eating smaller meals more frequently (as many as 6 small meals per day).

Weight gain formulas and supplements vary in quality. In general, the more dramatic the claims, the more skeptical you should be. Many weight gain formulas contain a lot of sugar and protein, usually in the form or whey or egg whites. In general, these aren't dangerous, but it would be better and less expensive to get the extra calories from real food.

However, you do need to be cautious about consuming excessive amounts of protein. First of all it does NOT build muscle. Any excess protein is simply burned for energy.

Excess protein consumption can lead to water loss. This is why your overweight friends lose a lot of weight the first couple weeks on a low-carb (high protein) diet. Excess protein overworks your kidneys and has also been shown to lead to an increased loss of calcium. Yes, men can get osteoporosis.

Amino acid supplements don't build muscle either. Amino acids are just the building blocks of protein and don't offer any special advantages. If you want to build muscle, you're going to have to exercise.

Physical activity burns calories, which may seem counterproductive for someone who is trying to gain weight. However, you should still try to get 30 minutes of physical activity per day to maintain your health. Strength training, in particular, builds muscle and helps ensure that weight gain is well distributed.

The Bottom Line