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Understanding high protein diets and their safety

Digestion, Weight loss | October 27, 2015 | Author: The Super Pharmacist

weight loss

Understanding high protein diets and their safety

Despite the variety of foods at our disposal, our bodies only use three macronutrients for caloric nutrition: fat, protein, and carbohydrate. Conventional wisdom is that healthy eating includes balanced amounts of each of these macronutrients. Self-proclaimed diet gurus and even some credentialed physicians have advocated diets that radically restrict one or two of these three macronutrients. One of the more popular macronutrient-restricted diets for people who wish to lose weight is the high-protein, low-fat diet. Will a high-protein, low-fat diet help someone lose weight and is this type of diet safe?

How a High Protein Diet (Might) Work

There are several reasons why a high-protein diet would be helpful for weight loss. When fat content is the same, diets high in protein help people feel full more than diets high in carbohydrates. In scientific terms, high-protein diets are associated with increased satiety. People also eat less when they are allowed to consume high protein diets rather than high carbohydrate diets. So even though a gram of carbohydrate and a gram of protein have the same amount of calories (4 cal), people feel full and eat fewer calories when consuming protein versus carbohydrates. Another advantage of a high protein, low fat diet is that it is reasonably easy to adopt and maintain.

How a High Protein Diet (Might) WorkThere are various lean meats and “low-carb” meal options available. Protein-containing powders can be used to help supplement caloric intake in place of food. In addition, since protein provides feelings of satiety, dieters do not feel as if they are starving or constantly fighting hunger pangs.

Carbohydrate-laden meals, especially those with simple sugars, tend to cause sharp elevations in blood insulin (i.e. high glycemic index). Insulin is released by the pancreas to help shuttle glucose and other sugars into cells and out of the bloodstream.

While proteins (certain amino acids, actually) stimulate insulin to a certain degree, they are less potent at stimulating insulin release than carbohydrates. These proteins also require the presence of carbohydrates. What does this all mean? The high-protein diet may be a better option for people with type 2 diabetes or insulin insensitivity. Moreover, meals with a low glycemic index reduce the number of calories consumed and may help promote weight loss.

Evidence from Clinical Studies

Clinical studies examining the efficacy of high-protein diets have been mixed. When study participants consume a low-fat diet combined with either high or low protein, there were only slight advantages in weight loss and waist circumference after being on the diet for an extended period. Importantly, these clinical studies did show that high protein diets provided higher satiety levels than low protein, low fat diets. Other studies have shown modest benefits to high-protein, low-fat diets with average additional weight loss of 2.3 kg. 

The important point is that total calories need to be kept low to achieve weight loss with any diet that restricts one of the three macronutrient types. Not surprisingly, low-fat, energy restricted diets where maximum daily calories are kept at a fixed amount result in weight loss. Individuals who had higher protein content (30% vs.15%) were more satisfied with these diets because they were less hungry than those who supplemented calories with carbohydrates. 

Are High-Protein, Low-Fat Diets Safe?Therefore, the key to weight loss is simply eating fewer calories than one currently does or than is needed to fuel the energy requirements of the body. The one possible advantage of a high-protein diet is that it is easier to stick to than a high carbohydrate diet, because dieters feel fuller when consuming high-protein meals.

Are High-Protein, Low-Fat Diets Safe?

The amazing thing about the human body, especially the young human body, is that you can do almost anything to it and it will adapt. So in young people without chronic health conditions, a low-fat high-protein diet is likely safe. If people have undiagnosed health issues, kidney disease, abnormalities in blood cholesterol, a tendency towards atherosclerosis, etc. this sort of diet may be less safe.

The main problem with high amounts of dietary protein is that it creates a relatively acidic environment for the body and increases the amount of calcium that the kidneys have to excrete. At the same time, calcium may be leeched from the bones, potentially weakening them. Taken together, this indicates that long-standing high-protein diets work to reduce bone mineralisation and may increase the risk for kidney stones. That said, small clinical studies to test for these adverse effects have shown that the diet is safe, calcium is not removed from bones (there is increased absorption from the gut), and bones may actually get stronger. 

While high protein, high fat diets may increase the risk of abnormal blood cholesterol levels and atherosclerosis, high protein, low fat diets do not appear to cause that same risk. Moreover, kidney function, as measured by creatinine clearance, appears to be unchanged by people who consume high-protein, low fat diets. Uric acid levels, which are associated with gout and a theoretical concern for people on high protein diets, also appear to be unaffected by this dietary approach.

Conclusion

Are High-Protein, Low-Fat Diets Safe?The key to weight loss is to consume fewer calories than the body needs to meet its energy requirements. Consequently, fat will be metabolised to meet the body's energy requirements and the dieter will lose weight. It does not necessarily matter how calories are restricted; however, high-protein, low-fat diets appear to be more palatable and easier to follow than high carbohydrate, low-fat diets.

Therefore, dieters are better able to adhere to these diets and are more likely to lose weight and maintain the weight that has been lost.

While anyone contemplating a new diet should first speak with a physician, available data suggests that high protein, low fat diets are safe for people without underlying health conditions.

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References

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