The big difference in the three nutrients as far as body fat levels goes is in number of calories per gram--4 for carbs and protein, 9 for fat--and something known as the thermic effect of food.
The thermic effect of food is the increase in metabolic rate that occurs as a result of the work the body has to perform in order to digest and store or utilize what is eaten. Each of the three primary energy sources--fat, carbs and protein--all have a different thermic effect. Fat requires about 3% of its caloric value, carbohydrate require about 8% of its caloric value, and protein requires between 20-40% of its caloric value to be expended in the digestion and storage process.
What this means is that for every gram of fat you ingest (9 calories' worth), .27 calories are expended in the digestion and storage or utilization process. For every gram of carbohydrate you ingest, .32 calories are expended in the digestion and storage/utilization process. For every gram of protein you ingest, .8-1.6 calories are expended in the digestion and storage/utilization process.
Whoaaaa! Big difference in the caloric cost of digesting/utilization/storage of protein vs. the cost for fat and carbs! Enough that if you compare a 2000 calorie per day diet that is 60% protein vs a diet that is 10% protein, you'll see a significantly different result.
Let's say that on the 60% protein diet, the remaining 40% of total calories will be divided equally between fat and carbohydrates. 1200 of the 2000 calories come from protein, 400 will come from fat and 400 will come from carbohydrate. Considering protein's thermic effect, digestion and storage of those 1200 calories will burn between 240 and 480 calories. The thermic effect of carbohydrate will burn about 32 calories and that of fat will burn about 12 calories, resulting in the total calories burned as a result of the thermic effect of food equal to between 288 and 524 calories.
On the same number of calories, but with the percentages as the food pyramid suggests, only 10% of the total daily calories will be coming from protein (200 calories' worth), meaning that the calorie expenditure accounted for due to thermic effect is now only 40-80 calories. If carbs account for 60% of the total daily intake (1200 calories' worth), the caloric expenditure related to the thermic effect for carbs is 96, and the caloric expenditure for fat at 30% of total calories (600 calories' worth) is 18 calories, resulting in the total thermic effect of food equal to between 154-194 calories per day.
What does this mean in terms of consumption? That if the majority of your calories come from protein, you will be able to eat more--130-330 calories per day more on a 2000 calorie per day diet--due to the higher overall caloric expenditure related to the thermic effect of food. Or, it also means that if you eat what appears to be the same number of calories in a day on a 60% protein plan vs a 10% protein plan, you will actually net less calories on the higher protein plan because of the increased number of calories burned as a result of the thermic effect of protein.
At the end of a month, using the conservative numbers for the thermic effect of protein, the higher protein plan yields a net calorie intake that is 3900 calories lower than the higher carb plan. Given that when weight is lost, even under the best of circumstances, the weight will come from fat, stored muscle glycogen and water, that 3900 caloric difference could possibly account for a huge difference in weight lost (easily close to 5 pounds' worth) at the end of a month on the two different eating plans--just as a result of the thermic effect of protein--even though both plans have exactly the same daily caloric intake!
What this means is that the higher protein diet will result in a greater expenditure than will the higher carb diet, even though the intake levels are the same calorically. The difference is in the expenditure. Weight loss is a matter of calories out exceeding calories in. It ain't magic, it ain't that carbs are evil, it ain't that ketosis causes fat loss, it ain't that excess protein calories can't be converted to fat--IT IS A CALORIES OUT VS. CALORIES IN THING!!!!!
This isn't a plug for high protein eating--merely a scientific explanation of the thermodynamics of how the differences occur. There are negatives of high protein eating, too--next post!
It is all a matter of balance!
Maribeth
The thermic effect of food is the increase in metabolic rate that occurs as a result of the work the body has to perform in order to digest and store or utilize what is eaten. Each of the three primary energy sources--fat, carbs and protein--all have a different thermic effect. Fat requires about 3% of its caloric value, carbohydrate require about 8% of its caloric value, and protein requires between 20-40% of its caloric value to be expended in the digestion and storage process.
What this means is that for every gram of fat you ingest (9 calories' worth), .27 calories are expended in the digestion and storage or utilization process. For every gram of carbohydrate you ingest, .32 calories are expended in the digestion and storage/utilization process. For every gram of protein you ingest, .8-1.6 calories are expended in the digestion and storage/utilization process.
Whoaaaa! Big difference in the caloric cost of digesting/utilization/storage of protein vs. the cost for fat and carbs! Enough that if you compare a 2000 calorie per day diet that is 60% protein vs a diet that is 10% protein, you'll see a significantly different result.
Let's say that on the 60% protein diet, the remaining 40% of total calories will be divided equally between fat and carbohydrates. 1200 of the 2000 calories come from protein, 400 will come from fat and 400 will come from carbohydrate. Considering protein's thermic effect, digestion and storage of those 1200 calories will burn between 240 and 480 calories. The thermic effect of carbohydrate will burn about 32 calories and that of fat will burn about 12 calories, resulting in the total calories burned as a result of the thermic effect of food equal to between 288 and 524 calories.
On the same number of calories, but with the percentages as the food pyramid suggests, only 10% of the total daily calories will be coming from protein (200 calories' worth), meaning that the calorie expenditure accounted for due to thermic effect is now only 40-80 calories. If carbs account for 60% of the total daily intake (1200 calories' worth), the caloric expenditure related to the thermic effect for carbs is 96, and the caloric expenditure for fat at 30% of total calories (600 calories' worth) is 18 calories, resulting in the total thermic effect of food equal to between 154-194 calories per day.
What does this mean in terms of consumption? That if the majority of your calories come from protein, you will be able to eat more--130-330 calories per day more on a 2000 calorie per day diet--due to the higher overall caloric expenditure related to the thermic effect of food. Or, it also means that if you eat what appears to be the same number of calories in a day on a 60% protein plan vs a 10% protein plan, you will actually net less calories on the higher protein plan because of the increased number of calories burned as a result of the thermic effect of protein.
At the end of a month, using the conservative numbers for the thermic effect of protein, the higher protein plan yields a net calorie intake that is 3900 calories lower than the higher carb plan. Given that when weight is lost, even under the best of circumstances, the weight will come from fat, stored muscle glycogen and water, that 3900 caloric difference could possibly account for a huge difference in weight lost (easily close to 5 pounds' worth) at the end of a month on the two different eating plans--just as a result of the thermic effect of protein--even though both plans have exactly the same daily caloric intake!
What this means is that the higher protein diet will result in a greater expenditure than will the higher carb diet, even though the intake levels are the same calorically. The difference is in the expenditure. Weight loss is a matter of calories out exceeding calories in. It ain't magic, it ain't that carbs are evil, it ain't that ketosis causes fat loss, it ain't that excess protein calories can't be converted to fat--IT IS A CALORIES OUT VS. CALORIES IN THING!!!!!
This isn't a plug for high protein eating--merely a scientific explanation of the thermodynamics of how the differences occur. There are negatives of high protein eating, too--next post!
It is all a matter of balance!
Maribeth
