The bottom line for losing weight is that you must create a caloric deficit. That means you must consume fewer calories than you burn. You can do this in two ways: reduce the number of calories in your diet or increase the amount of exercise you do. The most effective way is to do both simultaneously.
How to reduce your caloric intake
In principle, you could reduce your total caloric intake in one of two ways: either by eating the same foods you currently do and reducing portion sizes or by reducing intake of certain macronutrients (i.e., fat, carbohydrate, or protein). However, one of the challenges of dieting is that when your body senses that it is receiving fewer calories than it is burning, it responds by breaking down both body fat and muscle. For an athlete (and if you are rock climber, you should start thinking of yourself as an athlete), this is disastrous because when you diet you can potentially lose strength. Since we want to increase our strength-to-weight ratio, we want to maintain our muscle mass and lose weight in the form of body fat. The way to accomplish this through diet is to maintain carbohydrate intake, increase protein intake, and reduce fat intake enough to produce a caloric deficit.
We want to increase protein intake because the additional protein offsets the body’s increased rate of muscle breakdown while dieting. The reason it is important to maintain high carbohydrate intake is that the higher the carbohydrate intake, the less muscle tissue is broken down for energy (that is, dietary carbohydrate is muscle sparing). Dietary fat, on the other hand, is not muscle sparing; consequently, your entire reduction in calorie intake should come from reducing your intake of fats.
Let’s assume you are doing aerobic exercise for a half-hour 3 days a week and climbing indoors or out 3 sessions per week. (If you are not getting at least this much exercise, you should start. You will find it much easier to lose weight by a combination of diet and exercise than by just dieting.) The average female at this level of exercise will probably require about 2000 calories/day to maintain her body weight, while the average male will require about 2500 calories. You should try to consume about 500 to 750 calories per day less than you burn. This should result in losing 1–1½ pounds per week. This may seem too slow to some; however, more drastic diets do not work—they are virtually impossible to maintain.
OK, so now you have an idea about how many total calories to eat each day. The next question is how should these calories be distributed among protein, carbohydrate, and fat. My recommendations are the following: 25%–30% of the total calories in your diet should come from protein, 10%–20% from fat, and the remainder from carbohydrate. This is a low-fat diet that is relatively high in both protein and carbohydrate, as required to promote retention of muscle tissue. In order to operationalize this diet, you need to become savvy at reading nutritional labels and know that protein and carbohydrate contain 4 calories per gram and that fat contains 9 calories per gram (for those who need to know, it’s 7 calories per gram for alcohol).
So, what to eat
The challenge in this diet is keeping the protein intake high and the fat intake low. Therefore, you need to look for foods that are very low in fat and high in protein. Ideal foods are the following: beans, white-meat poultry, low-fat fishes (e.g., halibut), canned tuna, and soy-based non-fat mock meats (hint: think Trader Joe’s). You can eat essentially unlimited vegetables, since they are very low in calories. Fruits are essentially all carbohydrate and water and low in total calories, and can (and should) be eaten in moderation. Any grain products you eat should be whole grain, since they are higher in protein, fiber, and micronutrients than their processed counterparts.
Try not to add fat to anything. Throw away your mayonnaise, margarine, butter, and cooking oils. Pure oils such as these contain 120 calories per table- spoon. It is all too easy to turn a healthy, low-calorie salad into an abomination by adding excessive dressing. Instead of mayonnaise on sandwiches, substitute mustard (which is virtually calorie free), or just go without.
Keep a diary of everything you eat. Specifically note the total calories you consume and the total grams of protein in each meal. If, at the end of the day, you didn’t consume enough protein, have a blended shake made from a protein supplement and a piece of fruit in the evening. Buy the cheap soy-protein powder. Let the muscle heads waste their money on designer whey peptides.
I realize that this diet is more quantitative than some people would like. However, in my judgment, counting calories and protein grams is the only way to ensure adequate protein intake while maintaining a low-calorie diet. This is critical for athletes.