Healthy eating is complementary to physical activity in maintaining a lean weight, fitness, strength and all-round good health. In fact eating correctly can be crucial to sports performance and competition success in athletics, team sports and bodybuilding and powerlifting to name a few sports.
The question arises as to whether a very specialized diet limited in food choices has advantages over the generally accepted healthy eating pattern recommended by nutrition authorities and sports nutritionists.
In summary, healthy eating guidelines are:
- Eat plenty of fruit and vegetables, whole grains, beans, nuts and seeds; some lean meats, fish, eggs, and low-fat dairy products; and mono and polyunsaturated oils
- Limit intake of saturated fat, cholesterol, salt, alcohol and an excess of added sugars and sugary foods
- Drink plenty of water
- Maintain a normal weight
- Exercise regularly.
Even within these guidelines the percentages of macronutrients such as carbohydrates and fats and protein can vary. While the most recent dietary guidelines list the acceptable macronutrient distribution ranges for carbohydrate, fat and protein as 45-65%, 20-35% and 10-35%, respectively, trained dietitians and nutritionists would only very rarely recommend protein percentages higher than 25 percent of total calories.
Fad Diets and Extreme Diets
As many readers will know, special diets on the fringe of these ranges of macronutrients or food selection boundaries are common and popular as evidenced by the number of successful diet books doing the rounds. In any case, I have identified five types of dietary regimens that I call ‘extreme’ diets; not because they are necessarily unhealthy but because they are restrictive and require careful planning and nutrition knowledge in order to meet all the required nutrient requirements for health and energy purposes. Here they are:
- Very low-fat diets
- Very low-carb diets
- Vegan and macrobiotic diets
- Paleo diets
- Fad diets such as metabolic type, blood type, raw food
Let’s go through them one by one and deal with the ‘gotchas’ for each one – especially in relation to exercise and weight training where applicable.
Very Low-Fat Diets
Very low-fat diets are characterized by the Pritikin and Ornish diets which take the name of the creator. Both recommend that very low quantities of fat of any type is consumed, and this is usually in the range of 10-15 percent of total calories. The Ornish diet is a near-vegan diet with no meat and only low-fat dairy foods providing animal protein. No fish, nuts, avocados or olives are allowed. The Pritikin diet does allow some low-fat and lean fish, chicken and beef in small portions. Both emphasize mostly fruit, vegetables and whole grains and beans and little added sugar and refined grain foods.
Pritikin Longevity Center
Dean Ornish Lifestyle Program
What can go wrong with very low-fat diets?
Carbohydrates. A regular exercise program requires carbohydrates to fuel that exercise. It is the number one fuel for the more intense activities such as weight training especially if you combine it with circuit type training and strong cardio workouts. Very low-fat diets like Pritikin include a lot of high-fiber carbohydrates, usually 75 percent or more, so you won’t be deficient on a very low-fat diet.While refined and high-GI carbohydrates such as added sugar and white bread are not encouraged on these diets, if your exercise program includes high volume -- either intensity or duration of exercise -- you may find that you have trouble eating enough to fuel your activity if you consume a very high-fiber diet. Food fiber is bulky and creates satiety -- the feeling of being full. Some refined carbohydrates before, during or after exercise may be helpful.
On the other hand, as a general health consideration, low-fat, high-carbohydrate diets can go terribly wrong if you make the mistake of following the low-fat part without the high-fiber part. Diets high in refined carbohydrates and sugars tend to raise triglycerides and lower HDL, the good cholesterol, in the blood which may elevate heart disease risk.
Protein. While exercise, even weight training, does not demand an extraordinary amount of extra protein, it does require some extra, and serious weight training activities require the most. The very low-fat diets tend to de-emphasize protein intake, so you would need to ensure diet plans provide a solid protein supply in the range 1.5-2 milligrams/kilogram bodyweight/day. (Half this per pound of bodyweight.) Higher protein diets may assist with weight loss as well. Raising the protein content of very low-fat diets to at least 20 percent of caloric intake would go some way toward addressing protein requirements.
Essential fats. A regular criticism of very low-fat diets is that they could be deficient in the omega-3 and omega-6 essential fatty acids considering that nuts, avocados and oil seeds are generally discouraged and in the case of the Ornish diet, fish as well. The answer to this is to include at least some omega-3 rich fish such as salmon or sardines regularly and to be less strict with wholesome foods such as nuts and avocados. With a low fat intake also comes the risk of insufficiency, if not deficiency, of the fat-soluble vitamins A, E, K, and D.
Vitamin deficiencies. The Ornish diet risks being deficient in vitamin B12, iron and zinc because it precludes meat (see vegan diets below). Women require about 15 milligrams of iron each day, men about 10 milligrams and some athletes and heavy exercisers may require more. While fortified foods like breakfast cereals and soy milk can supply iron and B12 in useful amounts, a B12 supplement may be required in meat-free diets unless fortified foods can be identified and consumed regularly.
Summing up very low-fat, if you exercise regularly and intensely you must make sure you get enough energy, protein, fatty acids, iron and zinc in these diets.
