Understand This:
Consuming protein in the correct recommended amounts is important for weight maintenance and body composition for the following reasons:
- Protein can help to preserve lean (muscle) mass, which is especially important for athletes who are trying to lose body fat but maintain muscle mass.
- Protein is a very inefficient nutrient that provides the least amount of energy in comparison to carbohydrates and fat, so it can reduce energy intake on a minor level.
- Protein consumption can increase energy expenditure (to a small degree) via diet induced thermogenesis (increasing the body temperature).
- It is actually through this increased thermogenic effect that protein can promote a strong feeling of satiety. This feeling of satiety is the important factor in how protein can assist in weight loss because it can help to reduce overall food consumption by making you feel fuller with less food (energy).
Realize This:
Consumption of protein can help assist in weight loss by it's strong effect on satiety! This feeling of satiety is what helps reduce spontaneous energy intake and reduce overall eating. Consumption of protein does not help with weight loss because it provides less energy per gram in comparison to other macromolecules and increase energy expenditure via diet induced thermogenesis. These factors only play a very minor role in energy balance and are not significant enough to make any significant change in body weight.
A lot of individuals may lack protein intake when they are dieting for two big reasons:
- People feel protein intake is associated with weight gain, so they will reduce protein intake
- Since less food (energy) is consumed during a diet, it simply results in less protein intake as well. The portions of energy protein provides in a diet may be constant during the diet, but the absolute amount of protein consumed may fall below the recommended amount.
Optional reading: Why Protein is incorrectly associated with weight gain
Observational studies [13] from the 90’s have found that dietary protein content is positively associated with body fatness. That is why most of the diets from since then have been recommending reduced fat and protein diets to promote weight loss. However the problem with this observational study is that they failed to realize that most dietary protein comes from animal sources (meat, steaks, etc.) which are high in animal fat.
New findings from a recent Nurses’ Health Study found that increases in mono/polyunsaturated fatty acids (such as canola oil and olive oil) are not associated with weight gain, while increases in saturated fatty acids (animal fat) and trans-fat (hydrogenated polyunsaturated fatty acids) are positively associated with weight change [13*]. Based on these new findings it would seem that the observational study [13] from the 90's had in fact found an association between weight gain and the animals fat (embedded within the animal protein source, rather than with the protein itself).
What to Do:
During your diet it is important to eat to the recommended amount of protein. The current recommended dietary allowance of protein is: 0.8 grams / kg of body weight / day [14].
Example: If I am 100 kg, I will eat 80 grams of protein a day.
I stress it is critically important you concentrate on lean sources of protein such as chicken, fish, milk, and vegetarian sources such as chick peas, beans, tofu and lentils.
After you go through inducing satiation with dietary fiber, and you eat your main dish make sure one third to half of your plate is of a protein source. Make sure that you are eating the recommended daily amount of protein fit to your body weight. Consuming protein is crucial to promote satiety and help relieve your hunger (brain telling you, you are hungry) and rid you of your cravings.
Portion sizes are important I will post more articles on correct portion sizes!
Reference:
Rolls BJ: Carbohydrates, fats, and satiety. Am J Clin Nutr. 1995; 61: 960S ± 967S
Rolls BJ, Kim Harris S, Fischman MW, Foltin RW, Moran TH, Stoner SA. Satiety after preloads with different amounts of fat and carbohydrate: implications for obesity. Am J Clin Nutr 1994; 60: 476 ± 487.
Hill AJ, Blundell JE. Macronutrients and satiety: the effects of a high-protein or high carbohydrate meal on subjective motivation to eat and food preferences. Nutr Behav 1986; 3: 133 ± 144.
Hill AJ, Blundell JE. Comparison of the action of macronutrients on the expression of appetite in lean and obese human subjects. Ann NY Acad Sci 1990; 580: 529 ± 531.
Barkeling B, Rossner S, Bjorvell H. Effects of a high-protein meal (meat) and a high-carbohydrate meal (vegetarian) on satiety measured by automated computerized monitoring of subsequent food intake, motivation to eat and food preferences. Int J Obes 1990; 14: 743 ± 751.
Booth DA, Chase A, Campbell AT. Relative effectiveness of protein in the late stages of appetite suppression in man. Physiol Behav 1970; 5: 1299 ± 1302.
Astrup A, Raben A. Glucostatic control of intake and obesity. Proc Nutr Soc 1996; 55, 485 ± 495.
Rolls BJ, Hetherington M, Burley VJ. The speci®city of satiety: the in¯uence of different macronutrient contents on the development of satiety. Physiol Behav 1988; 43: 145 ± 153.
Stubbs RJ. Macronutrient effects on appetite. Int J Obes 1995; 19 (Suppl 5): S11 ± S19.
Hannah JS, Dubey AK, Hansen BC. Postingestional effects of a high-protein diet on the regulation of food intake in monkeys. Am J Clin Nutr 1990; 52: 320 ± 325.
Stubbs RJ, van Wyk MCW, Johnstone AM, Harbron CG. Breakfasts high in protein, fat or carbohydrate: effect on within-day appetite and energy balance. Eur J Clin Nutr 1996; 50: 409 ± 417.
Buemann B, Bouchard C, Tremblay A. Social class interacts with the association between macronutrient intake and subcutaneous fat. Int J Obes 1995; 19: 770 ± 775.
Field, A.E. et al. 2007. Dietary fat and weight gain among women in the Nurses’ Health Study. Obesity. 15: 967–976.
Douglas Paddon-Jones, Eric Westman, Richard D Mattes, Robert R Wolfe, Arne Astrup, and Margriet Westerterp-Plantenga. Protein, weight management, and satiety. Am J Clin Nutr 2008;87(suppl):1558S–61S.
Westerterp-Plantenga MS, Lejeune MP. Protein intake and body-weight regulation. Appetite. 2005 Oct;45(2):187-90.
For your scientific interest:
Protein is very unique in its ability to provide very little energy to the body yet have such a high satiating effect to help relieve hunger. Some of the proposed mechanisms for the reasons are as follows:
The body is very inefficient at storing proteins for energy. Due to this fact the body will actively oxidize and eliminate any excess amino acids so from this we gain very little energy from proteins. If proteins are to be used as energy they must first go through a biochemical reaction called “transamination” which converts the (protein) amino acids into (carbohydrate) glucose.
It is calculated by the Atwater factor for protein to provide 17 kJ of energy per gram. However due to the reactions proteins must go through before it can be used as energy, it actually only provides 13kJ of energy per gram to the body [39]. This is less energy than the same amount of carbohydrates or fat. The missing 4 kJ of energy are converted into heat (known as diet induced thermogenesis).
This Diet Induced Thermogenesis is theorized to increase satiety. It is fact that protein has the strongest effect on satiety and produces the most diet induced thermogenesis after consumption. However the reason for the cause is not known, and to tell you the truth I can’t even guess why. Scientists have found correlations that link feeling of satiety to the increased body temperature (so as body temperature drops again, satiety is lost and hunger returns).
There is a theory that suggests that the increased energy expenditure from the increased body temperature imply the body is undergoing physical activity which naturally required more oxygen intake by the lungs. Having a higher body temperature may wrongly signal to the brain the body is deprived of oxygen and translate to feelings of satiety.
Experiments found that people eating in a rooms with less oxygen (i.e. in higher altitudes) were full faster (experienced higher satiety) [15].
Muscle proteins are turned over fairly often; they will break down and rebuilt itself to maintain muscle mass. If there is not enough protein available in the body, protein cannot be built back up and result in muscle loss.
Side Notes:
High protein seems to help increase fat loss and weight loss. But how it is adverse to health?
High Protein diet and adverse effects on kidney function
A high protein diet is not found to have any effect on renal function on studies that follow up for as far as 11 years. However in the same 11 year study, it was found that renal function further declines in individuals who already suffer from kidney impairment. Another studies found that decreased dietary protein intake helped to slow the decline of kidney function compared to recommended protein intakes. I must mention that there are other studies that claim there are no renal impairments associated with a high protein diet, but the studies may not be long enough to make a safe conclusion because changes in kidney impairments would not be detect within the time span of the study (1 year).
So far with all the evidence we have from concurrent studies, it would seem that a high protein diet will have no decline in renal function in individuals with normal renal function.
Read More for your Scientific Interest
