Sometime ago, one of my middle-aged patients, who’s been struggling with her weight, followed up with me, around 20 pounds lighter. I felt happy to see her relatively trim, and looking fit.
Although I thought her weight loss was due to her daily gym exercises, she was quite convinced it was due to her low-carb, high-protein diet, which she started two months earlier.
She detailed to me her eating plan, which practically scrapped her carbohydrate sources and focused more on her increased protein intake. Unfortunately, her protein sources were mostly meat products.
I told her I had some reservations about this kind of diet, but since she seemed to be doing well with it, I said we would monitor her blood chemistry for any adverse effects. I suggested some modifications, though.
Theoretically, the scientific rationale of a high-protein, low-carb diet seems to be valid—by limiting carbohydrates, insulin levels in the blood may also be reduced. Insulin is required to metabolize carbohydrates and use them as an energy source for the body in the form of glucose.
In excess, though, insulin has bad effects on the blood vessels and has been implicated as a cause of their progressive blockage, leading to heart attacks and strokes.
Lower insulin levels induce the secretion of glucagon, another hormone secreted by the pancreas, which helps burn stored fat so it can be converted to energy. Glucagon does the opposite of insulin’s function: it raises blood levels of glucose. When blood sugar levels dip, glucagon causes stored carbohydrates (glycogen) in the liver to be released into the blood stream, increasing blood sugar levels. A regular increase of glucagon secretion induces fat loss and weight loss.
Furthermore, protein foods—which take longer to digest—give a longer feeling of fullness (satiety) than fats or carbohydrates. So, people on this type of fad diet tend to eat less and are more successful in controlling their appetites. Proteins also have a higher rate of thermogenesis; they require more energy to digest, and the increased energy consumption can contribute to weight loss.
However, the concerns with high-protein diets are equally valid, and must be thoroughly considered, preferably with the advice and guidance of one’s family physician. It is a restrictive type of diet, which can eliminate certain essential food groups also needed by the body. This may cause insufficiency of some essential phytonutrients, vitamins, minerals and antioxidants needed by the body.
There is one report showing that post-menopausal women on this type of diet are more susceptible to fractures due to the lack of some minerals leading to osteoporosis.
For people with pre-existing kidney problems such as in diabetics and hypertensive individuals, the high protein intake may tax the kidneys, aggravating kidney failure.
The increase in red meat intake as protein source, which some dieters resort to, is also not healthy, as it may increase the risk of cancer and heart diseases.
During the last scientific sessions of the American Heart Association two weeks ago, researchers presented the results of their study, suggesting that postmenopausal women (age 50 years or older) who follow a high-protein diet could be at greater risk of heart failure, especially if most of their protein comes from meat. The actual protein intake was documented by dietary self-reports combined with biomarkers to determine actual dietary protein intake, since self-reporting alone is not that reliable.
Risk of heart failure
The researchers noted that the risk of heart failure for women who regularly ate higher total dietary protein sources was significantly higher compared to women who ate less protein daily, or whose protein sources were mainly vegetables.
“Higher calibrated total dietary protein intake appears to be associated with substantially increased heart failure risk, while vegetable protein intake appears to be protective, although additional studies are needed to further explore this potential association,” explained Mohamad Firas Barbour, M.D., the main study author, who is a specialist in Internal Medicine at the Alpert Medical School and Memorial Hospital of Rhode Island, United States.
Several other studies have also shown similar association between increased protein from meat and cardiovascular risk in women. So, it may not be as safe as some advocates of high-protein diets say. For me, the best diet is still a well-balanced one.
For those who wish to lose weight, restricting calorie intake in a balanced way, combined with regular exercise and a strong will to attain one’s health goals, remains the most effective formula.