For some men, their problem gaining weight is as simple as not having enough of an appetite. They can do weight training every other day for an hour or so, participate in other active sports, yet not put on a pound. Some have success with brewer’s yeast, which has been known to stimulate appetite in some cases, but doesn’t work for others. (Australians and New Zealanders take brewer’s yeast in a singular concoction known as Vegamite, South Africans eat Bovril and Brits favor Marmite – brewer’s yeast spreads all.)

If lack of weight gain is a simple appetite problem, consult with your physician, and try eating 4 or 5 small meals a day instead of 3 heavy meals, since food is digested better it taken in smaller, more frequent portions. Avoid sugary junk food, making sure your diet is calorie-rich – load up on the complex carbohydrates, and eat a lot of protein and fats and fruit.
If you want to gain muscle mass, avoid anabolic steroids, which deliver short-term gain for long-term pain. Remember that most “hardgainers,” men who can’t seem to bulk up, are naturally lean, and won’t ever be mistaken for Charles Atlas. However, there are some ways they can get bigger.
Experts recommend such guys cut out drugs, cigarettes, and excessive alcohol consumption, since filtering out poisons takes the body’s time away from building muscle mass. Sleep at least seven hours each night for the same reason — give your body time to build itself.
Don’t waste time and money on nutritional supplements. In occasional cases mixed protein and carbohydrate powders actually help, consult your physician for advice. Eating 1/2 to 1 gram of protein per pound of body weight each day, spread out over 5 meals, is a good rule of thumb for gaining weight.
Working out with weights is the exercise you want to focus on, as such activities as running, stair climbing, and bike riding usually make it harder to gain weight. To keep fat gain off, try making workouts more aerobic by not resting as much during workouts. The safe way to do this is to alternate muscle group sets, so some are always resting while others work.