Susan M. Kleiner, PhD, RD, FACN, CNS

There isn't a more sizzling hot button in the nutrition community these days than the topic of protein and weight control. Add supplements and the discussion is on fire. So there are really two different issues within the title to this column: protein and weight control, and protein supplements and weight control. This column will discuss both.

Protein and weight control
The idea that your body needs more protein when you eat fewer calories is not new; I learned it in Nutrition 101. When looking for sources of energy, your body will choose carbohydrate and fat before it will use protein. Protein is unique among the macronutrients (protein, carbohydrate and fat) because only protein contains nitrogen. It is the nitrogen component of protein that allows for the building of new proteins, the manufacture of enzymes and hormones, and the growth and repair of tissues.

Since you are eating less, there is less carbohydrate and fat to use as fuel, so protein becomes an important energy source. This leaves less protein available to do the jobs that only protein can do. So you need to eat more. Simple.

How much more? If you don't exercise and you are restricting your calories to achieve weight loss, the amount of protein that you need to reach protein balance is about 60 percent more than what is needed by someone not trying to lose weight. A study conducted in Japan in 1987 estimated that while on an energy-restricted diet 1.26 grams of protein per kg body weight per day (about 0.6 grams/lb/day) was needed to achieve protein balance. (1)

Moderate exercise enhances the efficiency of protein utilization. You get more work out of each gram of protein when you exercise at about 40 to 50 percent of your maximal work capacity, even while dieting. If your weight loss strategy is to increase the calories you burn through moderate exercise rather than decrease the number of calories you eat from food, you might not need much more protein. (2)

But exercise at higher intensities does not enhance protein utilization. In fact, exercise at 65 percent or more of your maximal work capacity while dieting may decrease protein efficiency, greatly increasing protein needs. In this case protein needs may be as high as 2 grams of protein per kg body weight per day (about 1 gram/lb/day), or higher. (3) Even if you're just trying to maintain your weight, your protein needs will be higher if you are an intense exerciser.

Vegetarians that don't eat animal products also have higher total protein needs. Because plant proteins do not have the same array of amino acids as animal proteins, they do not support growth in animals as well as plant proteins and are considered lower quality proteins. Except for soy protein, all plant proteins are deficient in one or another amino acid and must be combined with other complementary plant proteins to fulfill the body's needs for complete protein sources of amino acids. Due to inferior biological quality, a higher quantity of plant protein must be consumed compared to animal protein recommendations. The general recommendation is that vegetarians who follow a diet limited in animal proteins should increase their total protein intake by 10% to achieve protein balance. This is especially important while following a weight loss diet. (4)

Finally, during any weight loss diet there is always some muscle lost along with the fat. This lowers metabolic rate and the amount of calories that you burn. But during a higher protein diet there is improved protein balance and reduced loss of muscle mass compared with a lower protein-high carbohydrate diet. This keeps metabolic rate higher, and makes weight loss easier. (5)

Along with meeting your basic physiological needs, more protein helps control weight in other ways. Lean protein helps stoke the fat-burning fires-its thermogenic (heat-producing) effect may be as high as 22 percent, compared with as low as 0.8 percent for carbohydrates. (6) You burn more calories by doing nothing more than eating more protein and fewer carbohydrates.

Associated with the thermogenic effect of protein is an increased sense of satiety. Women placed on high protein-moderate carbohydrate meals have a greater sensation of fullness during meals that lasts for longer periods of time between meals compared with low-protein meals. The difference is associated with the thermic effect of the meal. This means that by following a high protein-moderate carbohydrate diet you will feel more satisfied and have greater control over what and how much you eat. (6, 7, 8).

There are only a handful of studies investigating the impact that high protein diets have on total weight loss compared to low protein diets. A recent article in the Journal of the American College of Nutrition reviewed 15 studies that lasted for between 7 days and one year that followed comparable study designs. (6) Seven of the studies found a significantly greater weight loss with a higher protein diet, 5 of which were longer-term studies. The protein intakes averaged 24% of total calories from 4 of the studies, and one followed the very high protein intake typical of popular high protein diets. While weight loss was greater at 6 months, the study that lasted one year (very high protein diet) showed no difference between the groups at the 1-year point. Of the 8 studies that found no differences in weight loss between diet groups, half them were of a short duration and conducted with a small sample size of subjects, causing difficulty in accomplishing a statistically significant outcome.

Another interesting area of study is looking at whether a higher protein diet helps maintain weight loss and avoid regain after weight loss. One study found that increasing protein intake from 15% to 18% of total calories helped to reduce weight regain over time. When one puts together the weight of all the evidence, theoretical and actual research, it appears that it may be beneficial for weight control to increase lean protein by replacing some or all of the refined carbohydrates in the diet. (6)

Supplements and weight control
Practically speaking then, in place of reaching for pretzels or a bagel you should have a protein-packed snack instead. For many busy women this is easier said than done. While making a nice omelet would be a wonderful choice, most of us are not anywhere near a stove in the middle of the day. This is where supplements play a big role: as a convenient source of lean protein at the right time. When it comes to weight control, the research is supporting the practicality of the convenience.

Two studies, one 6-months and one 10 years, have shown that the convenience of meal replacement supplements was an important factor in their weight loss success. (9, 10) The 6-month study compared a group using a meal replacement product as part of their diet plan to a group on a conventional weight-loss diet. Meal replacement was equally effective for weight loss, and dietary compliance and convenience were viewed more favorably by those subjects consuming the meal replacements than by those in the conventional weight-loss program.

The long-term study tracked subjects following a meal replacement plan for 10 years. The product was provided free of charge. On average, the subjects weighed about 33 pounds less than people who didn't use a meal replacement plan at the end of the decade.

In a few words then, if you don't have a blender and some protein powder already, buy them. Even more convenient are the ready-to-drink shakes. What kind of protein powder or what kind of shake? That depends on your personal taste and on how you want to use your supplement.

• Egg (ovalbumen). At the top of the heap sit egg whites the reference standard against which other proteins are compared. Egg protein powders were once considered the best source of protein for supplements, but because egg protein is fairly expensive compared with other forms of quality protein, its popularity has decreased.
• Dairy. Casein, considered a slow protein because it is digested more slowly, and whey protein, a fast protein due its rapid digestion, are both heavy weights among protein supplements and both very high in quality. Whey is preferable immediately after exercise because of its rapid uptake, and casein is desirable for its timed-release action. Milk protein is also found as a supplement, containing about 80% casein and 20 % whey protein. The cost is usually lower than isolated casein or whey protein.
• Soy. Soy is a high-quality protein extracted from soybeans. Soy protein concentrate (70% protein) and isolate (90% protein) are particularly good protein sources for vegetarians. Soy protein also contains isoflavones, which have a number of potential health benefits. If you are having trouble getting in your soy each day, this is a convenient strategy. But you won't be getting in the healthy soy fibers unless your product contains both.

I have to admit that I prefer a homemade smoothie compared to a ready-to-drink beverage, and so do most of my clients. They have found ways to use their blender in the most interesting places. Many have a blender at work where they can whip up one of the recipes that I have included here. A number make several at a time at home and freeze them, taking one in their gym bag to work and then the gym. By the time they're finished with their workout, they just shake and drink. The most unusual setting has been out on the road in a car. A client in sales who spends a lot of time in his car carries his dry ingredients and a cooler with frozen fruit and milk. He plugs his blender into his car battery and has a homemade smoothie to go!

Whatever works for you, whole food or supplement, make sure to have a source of protein with every meal and snack. It will help to keep your appetite in check, your metabolic fires stoked, and your weight under control.

Kleiner's Essential Recovery Formula
-if you are trying to lose weight and want to give your body it's most critical recovery nutrients after exercise, this is the recipe for you.

.25 cup frozen strawberries
.25 cup nonfat strawberry yogurt
.25 cup nonfat milk
.25 cup calcium-fortified orange juice
15 grams protein supplement

Blend until smooth.
Makes one serving. Each serving contains: 155 calories; 20 g carbohydrate; 20 g protein; 0 g fat; 1 g dietary fiber. Equivalent to 1 fruit serving, 1 milk serving, 2 very lean protein servings

Kleiner's High Protein Meal Replacement Formula
24-25 grams protein isolate
1 cup frozen unsweetened berries
½ cup orange juice
8 ounces skim milk
1 tsp flaxseed oil

Blend until smooth.
Makes one serving. Each serving contains: 341 calories; 42 g carbohydrate; 32 g protein; 5 g fat. Equivalent to 2 fruit serving, 1 milk serving, 3.5 very lean protein, 1 fat serving

References

1. Y O, Okuda T, Koishi H, Koh H, Waki M, Kurata M, Nambu S. Relationship between protein intake and nitrogen balance in obese patients on low energy diet. J Nutr Sci Vitaminol 1987;33(3):219-26
2. Todd KS, Butterfield GE, Calloway DH. Nitrogen balance in men with adequate and deficient energy intake at three levels of work. J Nutr 1984;114(11):2107-18
3. Butterfield GE. Whole-body protein utilization in humans. Med Scie Sports Exerc 1987;19(5 Suppl):S157-65
4. National Research Council. Recommended Dietary Allowances, 10th Edition. National Academy Press, Washington, DC, 1989
5. Agus MS, Swain JF, Larson CL, Eckert EA, Ludwig DS. Dietary composition and physiologic adaptations to energy restriction. Am J Clin Nutr 2000;71(4):901-7
6. Halton TL, Hu FB. The effects of high protein diet on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr 2004;23(5):373-385
7. Westerterp-Plantenga MS, Rolland V, Wilson SA, Westerterp KR. Satiety related to 24h diet-induced thermogenesis during high protein/carbohydrate vs high fat diets measured in a respiration chamber. Eur J Clin Nutr 1999;53(6):495-502
8. Crovetti R, Porrini M, Santangelo A, Testolin G. The influence of thermic effect of food on satiety. Eur J Clin Nutr 1998;52(7):482-8
9. Noakes M, Foster PR, Keogh JB, Clifton PM. Meal replacements are as effective as structured weight-loss diets for treating obesity in adults with features of metabolic syndrome. J Nutr 2004;134(8):1894-9
10. Health Day News, October 13, 2004. Meal replacement plans do work. Study presented by Dr. George L. Blackburn at the North American Association for the Study of Obesity annual meeting in Fort Lauderdale, October 13, 2004.

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