When it comes to dieting, in or out of bodybuilding, a theory is born every minute. Yet how can so many different approaches, based on contradictory beliefs about how the body works, all allow you to shed the pounds? What ingredients do all these diets have in common? Science hasn't been much help in the matter to this point. Past research studies were designed to examine the effect of various diets on weight loss, but most have been contradictory or inconclusive. But a recent study published in The American Journal of Clinical Nutrition seems to shed new light on this complex subject. According to the report, the composition of the diet isn't the main factor when it comes to losing bodyfat. The most important thing is calories.

To put it another way, when it comes to losing bodyweight, the amount of food energy you take in (balanced against your energy expenditure) is what really counts, rather than what kinds of calories (protein, fat, carbohydrates) your diet consists of.

INTAKE DETERMINES WEIGHT LOSS
The word calorie is really just a measure of heat, and therefore energy. Protein contains 4 calories per gram, as does carbohydrate. Fat, on the other hand, is more energy dense at 9 calories per gram. Each nutrient has a different biochemical structure and performs different functions in the body. But once broken down by the digestive system, all food is made up of carbon, hydrogen, and oxygen, with protein also containing nitrogen. At a fundamental level, then, a calorie of energy is a calorie of energy, regardless of its source.

This statement challenges several widely held assumptions, including that carbohydrates make you fat and that ingesting fat will cause you to store bodyfat at a disproportionately high rate. The new study was developed to determine whether any of these common theories was true, or whether success in dieting was more a matter of caloric deficit than specific nutritional balance.

Of course, when you're trying to lose bodyfat, how much protein you eat is also important. You can't build or maintain muscle mass if you deprive yourself of sufficient protein. In this study, the subjects - who were obese - were given adequate amounts of protein and they exercised regularly, which is also necessary to conserve lean body mass. They were placed on reduced-calorie regimens, with each group taking in the same amount of calories per day, but their diets were composed of slightly different amounts of protein and considerably different amounts of carbohydrate and fat.

DIET 1:
32% of calories from protein, 15% from carbohydrate, 53% from fat.

DIET 2:
29% of calories from protein, 45% from carbohydrate, 26% from fat.

The result was a similar degree of weight loss in both groups (about 17 pounds) over a six-week period, indicating that it was energy intake, not nutrient composition, that determined weight loss in response to low-energy diets over a short time period.

This result shouldn't be that surprising. After all, fat stores in the body represent an energy surplus. The logical way to reduce your body's fat stores, then, is to create an energy deficit - to take in less energy than your body requires over a given period of time. Of course, several health hazards are associated with eating too much fat, including greater risk of heart disease and certain cancers, but this research doesn't involve high-fat, high-calorie diets. Rather, this is about low-calorie diets that contain a greater or lesser percentage of fat vs. carbohydrate.

TRAINING, PROTEIN & FEWER CALORIES
Analyzing this study, you can see it was almost designed with bodybuilders in mind. For example:

- The subjects were required to exercise during the course of their diets. Exercise not only burns additional calories, but helps prevent loss of lean tissue.

- The caloric intake for each subject was distributed over four meals (breakfast, lunch, dinner, bedtime snack) rather than the traditional three. As a rule, bodybuilders eat at least four meals a day, sometimes more.

- While the protein content of the two diets varied, it didn't vary by much, and in both cases was sufficient to prevent the loss of muscle tissue due to protein deprivation. No matter what kind of diet bodybuilders are on, it almost invariably involves high protein consumption.

- The combination of low calories plus exercise created a sufficient energy deficit to result in significant weight loss over a relatively short period.

Yet the results of this study don't mean that bodybuilder A is correct in his diet and bodybuilder B is wrong. Quite the opposite. Any approach to fat-loss, muscle-sparing dieting that you're comfortable with - high or low carbs, high or low fat, eating dairy, not eating dairy, eating fruit or wheat or not eating those foods - is probably going to work as long as you:

1. Create an energy deficit with a combination of low calories and exercise.
2. Train your muscles correctly.
3. Eat enough protein to sustain your muscle mass.

"I'm not that surprised by the findings of this study," says Armand Tanny, MUSCLE & FITNESS writer and former Mr. USA. "Over the years, bodybuilders have tried a lot of different diets. I've seen some pretty strange approaches to dieting, let me tell you. But the one thing they all had in common, if they were successful, was taking in less food - reducing calories. That's the unchanging common denominator."

In fact, this study is unlikely to change the dietary practices of most of today's top bodybuilders. They tend to keep their protein intake high, limit both fat and carbohydrate to reduce calories as much as possible, and further encourage an energy deficit with daily aerobic exercise. Those three factors - training, protein, low calories - are what make the bodybuilding diet work so well.

The research findings, however, should help to assure those who believe that eating any significant amount of fat will cause their bodies to produce excessive fat, or who think that allowing more than a tiny amount of carbohydrate into their diets will lead to an inevitable weight gain. When it comes to losing weight, the valid approach seems to be to eat enough protein to maintain muscle mass and create a calorie deficit (by eating less and exercising more) sufficient to cause a reduction in bodyfat.

THE BODYBUILDING DIET: CALORIES AND MUCH MORE
"Dieting for bodybuilders is more demanding than for the average person who's into fitness," says MUSCLE & FITNESS associate publisher Tom Deters, DC. "Bodybuilders aren't just concerned about fat loss. Their goal is an alteration of body composition, which involves both the loss of bodyfat and the maximum development of muscle mass. This involves a lot more than just cutting calories."

Nowadays, bodybuilders are probably the most successful dieters on the planet. They build muscle, lose fat and achieve a condition of hard, ripped definition on a precise schedule. They use a variety of approaches to dieting, but since the early days of the sport, competitors have understood that reducing caloric intake is one key to maximum fat loss.

"The bodybuilding diet evolved pretty much on a trial-and-error basis," says Larry Scott, the first Mr. Olympia. "When I first started bodybuilding in the 1950's I was taught to eat high protein and high fat and to drop my carbohydrate intake to get defined. Now, most bodybuilders don't believe in high-fat diets, but most of them do limit their carbohydrates. They also do a lot more aerobics than we ever did. If you look at the physiques of the champions decade by decade, you can see the difference. There has been real progress when it comes to getting cut and muscular for contests."

One thing bodybuilders have learned is that the same diet doesn't necessarily work equally well for everybody. The reasons are both physiological and psychological. For example, bodybuilders don't just exercise - they train. Some feel too weak to get the best out of their workouts on diets too low in fat or carbs. Some can achieve adequate fat loss on highly restricted diets with little aerobics, while others feel they need to eat more and make up the caloric difference with hours of cardio work on a treadmill or exercise bicycle.

"The different approaches to diet are endless," explains bodybuilding legend Bill Pearl. "I've known bodybuilders who couldn't face a workout without first sitting down to a big steak. I'm a vegetarian, so that wouldn't work for me, but I haven't noticed any letdowns in my own workouts because I don't eat meat."

Yet all the top champions agree on one thing: You won't lose bodyfat unless you place your body in a state of caloric deprivation. That is, it isn't going to use up its supply of stored energy unless you take in less energy than you expend in any given time period. No matter what the composition of your individual diet, it won't get results if you eat too much and exercise too little.

The bottom line seems to be that once you satisfy your protein requirements on a low-calorie diet, what percentage of those remaining calories are carbohydrate and fat is not, in itself, significant when it comes to losing bodyfat.

THIS INFORMATION IS FOR EDUCATIONAL PURPOSES ONLY. IT IS NOT MEDICAL ADVICE AND IS NOT INTENDED TO REPLACE THE ADVICE OR ATTENTION OF HEALTHCARE PROFESSIONALS. CONSULT YOUR PHYSICIAN BEFORE BEGINNING OR MAKING CHANGES IN YOUR DIET, SUPPLEMENTS OR EXERCISE PROGRAM, FOR DIAGNOSIS AND TREATMENT OF ILLNESS AND INJURIES, AND FOR ADVICE REGARDING MEDICATIONS.