Fit for fat: can eating too lean starve your muscles?

Men's Fitness, April, 1999 by Dave Tuttle

Can eating too lean starve your muscles?

For years, athletes have lived by one maxim: No fat is good fat. In their quest for improved performance and enhanced looks - as well as protection from cardiovascular disease - professional and weekend athletes have obsessively eradicated fat from their daily menus. New research is showing, however, that overzealousness in eliminating dietary fat may be a mistake. Far from hurting performance, an appropriate amount of the right fat can actually improve your game and promote muscle growth.

Extremely low-fat diets - under 15 percent of total calories - have been linked to a number of maladies, including a suppressed immune system, decreased endurance and muscle strength, vitamin deficiencies, hair loss and skin conditions such as eczema and psoriasis. In a study conducted at the State University of New York at Buffalo, subjects on a low-fat diet manifested calcium, magnesium, zinc and vitamin E deficiencies. When the same subjects boosted their fat intake, their vitamin and mineral levels increased while their heart rates, body fat and cholesterol levels remained the same.

Good fat, bad fat

Body fat is merely energy (calories) that is stored rather than used. If you ate 6,000 calories of nonfat protein, you would still get fat simply because you'd be eating more calories than your body can burn. All fats have nine calories per gram and should be avoided by people trying to lose weight, but they differ from each other in a number of important ways. The type of fat you eat is as important as the amount. By eating fat that actively contributes to your body's assembly line - instead of the kind that hangs around clogging up arteries - you can feel and play your best.

Ideally, your fat intake should hover between 20 and 25 percent of total calories. The majority of this should come from essential fatty acids and monounsaturated fats. Remember, if you choose to boost your fat intake, you may have to cut back on carbs so that your daily calorie count doesn't skyrocket out of control.

Essential fatty acids are "essential" because your body cannot manufacture them, so your diet must include sufficient amounts. EFAs are vital for regulating hormone balance and immune function, and they help maintain hair, skin, nerves and arteries. The two EFAs are omega-3 and omega-6 fatty acids. Omega-6s are in many processed foods, so most Americans invariably get enough of them. Omega-3s are a little harder to come by. Flaxseed oil is an excellent source (as are the less common and more expensive evening primrose and borage oils). Use two or three tablespoons of flaxseed oil a day as a part of salad dressings, marinades or dips, or just mixed into a protein shake. Eating coldwater fish, such as salmon or mackerel, several times a week is also a good way to get your omega-3s.

Believe it or not, monounsaturated fats are actually good for your heart. Not only do they lower LDL (the "bad" cholesterol), but a study published in the Annals of Internal Medicine indicated that people who ate diets that were higher in monounsaturated fats lived longer and had less incidence of cancer than those on low-fat regimens. Researchers at the University of Rochester in New York found that by substituting monounsaturated fats for saturated ones, dieters lost weight and felt more satisfied even though they consumed an identical quantity of fat grams.

Better than most but worse than some, polyunsaturated fats are found in safflower, soybean and sesame oils. Chemically unstable and quick to oxidize, they can damage DNA and cell membranes. But it's saturated fats, those scientifically correlated contributors to heart disease and cancer, that give fat a bad name. Unfortunately, they also provide the great taste in red meat, egg yolks, butter, cheese and other whole-dairy products.

Could anything be worse for you? Absolutely. Recently discovered fats known as trans-fatty acids are created in the process of deep frying; they are also found in vegetable shortenings, margarine, hydrogenated vegetable oils and, therefore, in virtually any commercial package of crackers, cookies or cakes. A study published in the New England Journal of Medicine showed that TFAs, more than any other type of fat, are linked to the highest rate of heart disease.

Pumping fat

Fat intake plays a major role in strength gains and sports performance. First, the fatty acids found deep inside your muscle cells can be utilized for energy during intense, short-term activities (like weight training) as well as aerobic activities. Unlike glycogen metabolism, this process does not result in lactic-acid production, so you can exercise longer with less discomfort. In the Buffalo study, researchers discovered that higher fat levels in the diet increased fat oxidation during exercise. This spared the glycogen and increased maximum aerobic power. A second study at the university found that athletes consuming higher levels of fat ran farther than those on relatively fat-free diets before reaching exhaustion.