Why protein matters in low calorie diets

From Healthwise. Why you should avoid Carbs and Eat More Protein!

The importance of protein within the context of low calorie diet cannot be underestimated. The use of
supplemental protein in the diet has several important functions.

Protein plays a major role in the structure and function of the body. It is an important structural
component of cells, hair and nails. It is an integral part of skin, bones, muscles, blood and connective
tissue.

Without adequate protein, our immune systems wouldn’t function properly and our bodies would have difficulty producing adequate hormone levels. In fact, every metabolic function that occurs in the
body depends upon the presence of proteins called enzymes.

Even when not dieting, the proteins that make up our muscles are constantly being turned over. As
our caloric intake decreases, the body will begin using these proteins from our muscles to meet its
energy needs. Ideally, during dieting, the goal is not just weight loss, but rather fat loss and muscle
maintenance or gain.

For this to occur, our overall caloric intake must decrease while maintaining
adequate protein consumption. As muscle mass increases, so does one’s resting metabolic rate. This,
in turn, allows the body to burn more calories during rest, regular activities of daily living and with
exercise. Another benefit to a proportional increase in dietary protein is the increased satiety it provides.

Gram for gram, protein tends to satisfy and decrease hunger better than either fats or
carbohydrates. This helps improve a dieter’s chances of success by reducing the chronic hunger
that so often comes with calorie reduction.

Recommended amounts of protein vary depending upon one’s age, gender and current fitness and
activity levels. The suggested range begins at 0.8 grams of protein per kilogram of lean body weight
per day to upwards of 1-1.5 grams per kilogram of lean body weight for the very seasoned and muscular athletes.

As one begins dieting, a positive nitrogen balance can easily be maintained with the addition
of supplemental protein in the form of protein bars or protein supplements. This is a very good way to
ensure adequate protein while keeping total calories low.

In the context of an LCD diet or protein sparing modified fast, the reduction of carbohydrates has
equally important consequences. The hormonal changes associated with low carbohydrate diet include
a reduction in the circulating levels of insulin along with increased levels of glucagon. Insulin has
many actions, the most well-known of which is stimulation of glucose and amino acid uptake from
the blood to various tissues. This is coupled with stimulation of anabolic processes such as protein,
glycogen and fat synthesis.

Glucagon has opposing effects, causing the release of glucose from glycogen
and stimulation of gluconeogenesis and fat mobilization. Thus, the net stimulus would seem to be for
increasing muscle protein breakdown. However, a number of studies indicate that a low carb diet results in body composition changes that favor loss of fat mass and preservation in muscle mass.

According to G.L Blackburn's study carbohydrate apparently does not improve protein sparing. In
studies have shown that obese patients on a diet containing 40 grams of protein experienced
significantly better nitrogen balance than patients on an isocaloric diet in which 26 grams of
carbohydrate replaced some of the protein.

There is another theoretical advantage to omitting carbohydrate from a very low calorie diet. If a diet contains the minimum amount of protein needed to prevent loss of lean body mass, addition of carbohydrate adds calories and will therefore decrease the rate of weight loss.

In a recent randomized trial in 17 healthy obese women, a diet containing 1.5 gm
protein/kg ideal body weight was found to result in significantly better protein sparing than an isocaloric
diet providing only .8 gm protein/kg ideal bodyweight.' Patients lost weight at the same rate on the two
diets, but since there was less nitrogen loss on the diet without carbohydrate, it can be assumed that
more fat loss occurred than on the diet where carbohydrate replaced some of the protein.

What implications does this have regarding the choice of the protein supplements mentioned in the
protein discussion? It means that for the benefit of both the health and success of the dieter, the selection
of protein supplements should focus not only on the taste but on the nutritional composition of the
supplements..

The best choice is to avoid higher carbohydrate, low protein supplements and to select
supplements that are higher in protein and lower in carbohydrate content. The conclusion would be
that for products that are relatively similar in carbohydrate content, the preferred choice would be the
protein supplement that offers a higher protein content and a taste that the patient find both pleasing and
acceptable.