The main problem with forced calorie restriction diets is the fact that after a while, you feel hungry. It may take a week, a month or a year, but sooner or later most people who cut calories get hungry. This causes an increase in food intake which ultimately causes weight regain. Controlling appetite is therefore paramount if weight loss is to occur. The protein leverage theory states that protein might offer some assistance in this regard.
The Protein Leverage Theory
The protein leverage theory suggests that each animals has a requirement for amino acids. Amino acids are found in protein, and therefore dietary protein provides the necessary amino acids. If lower protein foods are eaten, then compensatory increases in food intake occurs to maintain the minimum amino acid intake. Higher protein foods satisfy the requirement for amino acids more quickly and so less total food in consumed.
High Protein Foods Cause Weight Loss
The protein leverage hypothesis might explain why high protein diets cause weight loss. Increasing the protein intake causes satisfaction of the protein requirements at a lower total calorie load, and as a result appetite is down regulated to prevent additional food intake. Supplementing the diet with protein powder would have the same effect as eating high protein foods in that it would provide the protein requirements at a lower total load of energy.
Most Foods Are Devoid Of Protein
When you are out and about, finding high protein foods is difficult. It is only when you try to find such foods that you realise that most Western food is carbohydrate based. If the protein leverage hypothesis is correct, people eating such foods will not satisfy their protein requirements and so appetite will be stimulated to increase protein intake. Under such conditions, only at very high calorie intakes with protein requirements be met, thus facilitating weight gain.
Exercise Increases Protein Requirement
If the protein leverage hypothesis is true, then protein requirement is likely not fixed. Exercise, particularly resistance training is known to increase the requirement for dietary protein. Therefore undertaking resistance training would create a higher set point for protein compared to the untrained state. Protein supplements are probably necessary under such conditions so as not to facilitate the consumption of too many calories to satisfy amino acid requirements.