I can’t gain weight! Is my metabolism too fast?

Dear Cecil: I have this problem of being underweight. I’m a male, 22, 5'10", and weigh only 125 pounds. I don’t know what the cause of it is, but whatever I eat and whatever I do I can’t seem to gain any weight. I have taken some weight-gaining tablets and drinks, but they don’t help. I have just started some body building, which might help, but I doubt it. People tell me my metabolism must be going too fast. So my questions are: (1) Is my metabolism going too fast? (2) If it is, when will it slow down? (3) Do you have any advice that will help me gain at least ten pounds? R.E., Washington

Cecil replies:

You realize, R., that yours is a problem two-thirds of North Americans would love to have. Not that that’s much comfort, I’m sure. I’ve heard this “fast metabolism” stuff for years, and as far as I’ve been able to discover it’s nonsense. Differences in basal metabolic rate (a measure of the rate at which the body burns energy while at rest) per unit of body weight among healthy individuals of the same sex are relatively minor. Major differences are usually accounted for by some disorder like hyperthyroidism. If you have any suspicions in this regard, see a doctor.

Illness aside, you may have poor eating habits or an excessively frantic lifestyle–stress tends to increase the metabolic rate. I’ve heard other explanations for chronic thinness, but they all sound pretty dubious. For instance, one of my doctor buddies has advanced the proposition that body weight is related to the length of your small intestine–the longer it is, supposedly, the more food you absorb. Sure, doc.

The most straightforward explanation is that people who have a hard time gaining weight (what we refer to as ectomorphs) simply have fewer muscle and fat cells to absorb the extra bulk than more athletic types. Fortunately, tests have shown that weight training can add new muscle cells, a process called hyperplasia. This is a lot more work than simply strengthening existing muscle cells, admittedly, but you can take some comfort in the fact that the new muscle cells stay with you all your life, even if you knock off weight training later on.

What you need is a systematic weight gain program: eating (lots of carbohydrates, a fair amount of protein, no junk) plus weight lifting, with an emphasis on upper body exercises–six to eight repetitions per exercise with heavy weights. Increase the weight as soon as you can do more than eight reps. Patience is advised. The common wisdom among weight lifters is that you can gain about seven pounds of pure muscle a year. This may seem a little slow, but it can be done as long as you have the Proper Attitude. You think Arnold Schwarzenegger said, “It might help but I doubt it”?

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.