Recently, The New England Journal of Medicine (NEJM) published a study comparing the effects of different diets on weight loss. Their conclusion? It doesn't matter what you eat, only how much you eat. So, pick a diet you can stick with, as that's all that really matters.
It's only partially true.
How much you weigh is a balance between calories in--how many you eat--and calories out--how many you burn, i.e., how much you exercise. The laws of thermodynamics haven't changed recently.
However, it is emphatically not true that all foods are equally healthful. In general, losing weight is a good thing for those who are overweight, but it's important to lose weight in a way that enhances your health rather than one that may compromise it.
Although many news reports of this study made it seem as though the researchers were comparing an Atkins diet with the way of eating that I recommend, they weren't. One of the major reasons that an Atkins diet may be harmful to your health is that it raises LDL-cholesterol, sometimes referred to as "bad cholesterol" because it is the fraction of cholesterol most strongly linked with coronary heart disease and stroke.
One of the reasons that it raises LDL-cholesterol is that red meat, eggs, bacon, brie, and butter--the foods that Dr. Atkins used to say are really good for you and your heart--are rich in saturated fat and dietary cholesterol, which have been shown in numerous studies to raise LDL-cholesterol. Atkins acolytes such as Gary Taubes continue to say that saturated fat and dietary cholesterol do not affect your blood cholesterol level despite decades of research clearly showing that they do. (He also writes that exercise does not help you lose weight--being a contrarian is one thing, being obtuse is another.)
In the recent NEJM study, the researchers significantly limited the intake of saturated fat and cholesterol in all of the diets that they tested. Specifically, they limited dietary cholesterol to less than 150 mg per day--this is half of what the American Heart Association recommends for a heart-healthy diet. They also limited the intake of saturated fat to less than 8% of calories per day, which is also essentially what the American Heart Association recommends. This is not surprising, since the lead author of the NEJM study, Dr. Frank Sacks, who is one of the country's leading nutrition researchers, is also vice-chairman of the American Heart Association's nutrition committee and co-authored their dietary guidelines.
In other words, all of the diets were made heart-healthy. Significantly limiting the amount of saturated fat and dietary cholesterol in an Atkins diet is like, well, putting lipstick on a pork rind.
Even so, the NEJM researchers found that "At 2 years, the two low-fat diets and the highest-carbohydrate diet decreased LDL-cholesterol levels more than did the high-fat diets or the lowest-carbohydrate diet (low-fat vs. high-fat, 5% vs. 1%; highest-carbohydrate vs. lowest-carbohydrate, 6% vs. 1%."
In other words, the low-fat/high carbohydrate diets decreased the fraction of cholesterol most strongly linked with heart attack and stroke five to six times more than did the high-fat/low-carbohydrate diets. And this was after asking those on an Atkins-type diet to significantly limit their dietary intake of cholesterol and saturated fat, which is likely why LDL-cholesterol did not increase on the Atkins diet as it has it other studies.
Despite this finding, The New York Times wrote, "For people who are trying to lose weight, it does not matter if they are counting carbohydrates, protein or fat. All that matters is that they are counting something." The Associated Press wrote, "Low-fat, low-carb or high-protein? The kind of diet doesn't matter, scientists say. All that really counts is cutting calories and sticking with it, according to a federal study that followed people for two years."
It may not matter if all you're concerned about is losing weight, but it does matter if you're concerned about losing your health. Studies that measured blood flow rather than only risk factors such as cholesterol levels found that blood flow and inflammation worsened in those who consumed an Atkins diet but not in those following the dietary guidelines I recommend, causing these researchers to conclude that "the Atkins diet may negatively impact cardiovascular health." Another study showed that heart disease got worse on an Atkins diet.
HDL-cholesterol levels were a little higher on the low-carbohydrate diet than on the low-fat/high carbohydrate diets, but as I have written about many times before, a rise in HDL in the context of eating a high-fat diet is not necessarily beneficial. Your body makes HDL to remove excessive cholesterol from your blood and tissues, a process known as "reverse cholesterol transport." When you eat more fat and cholesterol, your body makes more HDL. The easiest way to increase your HDL is to eat a stick of butter.
In contrast, my colleagues and I have published numerous studies showing that when people follow a very low-fat diet rich in fruits, vegetables, whole grains, legumes, and low in refined carbohydrates along with moderate exercise, stress management techniques, and social support, their health improves dramatically. My colleagues and I at the nonprofit Preventive Medicine Research Institute and the University of California, San Francisco, have studied this diet and lifestyle program for more than three decades and published our findings in the leading peer-reviewed journals.
We reported in a randomized, controlled clinical trial published in the Journal of the American Medical Association a 24-pound weight loss after one year and 13-pound average weight loss after five years in a group of men and women, much more than weight lost in the NEJM study. These findings were replicated in larger demonstration projects as well. Using state-of-the-art measures in randomized controlled trials, we found that this program caused reversal of coronary heart disease after only one month, even more reversal after one year, and still more improvement after five years. This is why Medicare is now covering intensive lifestyle programs such as this. We also measured a 40% decrease in LDL-cholesterol levels after one year in a free-living group of men and women without cholesterol-lowering drugs.
We also conducted a randomized controlled trial showing that this program was able to stop or even reverse the progression of early prostate cancer and, by extension, may affect breast cancer as well.
Our latest study showed that these diet and lifestyle changes caused beneficial changes in gene expression in over 500 genes in just three months-"turning on" disease-preventing genes and "turning off" genes that promote heart disease, cancer, and other illnesses. And we found increases in telomerase, and thus telomere length, by 30% in only three months. Our telomeres are the ends of our chromosomes that control how long we live--the longer our telomeres, the longer we live.
Dr. Atkins and I agreed that too many refined carbs such as sugar, white flour, and concentrated sweeteners are harmful. Because these are low in fiber, you can consume large amounts without getting full. Also, these are absorbed quickly, causing blood sugar levels to spike; this, in turn, causes insulin surges. Too much insulin accelerates the conversion from calories into fat. Over time, insulin surges may lead to insulin resistance and, ultimately, type 2 diabetes.
However, fruits, vegetables, whole grains, legumes, and soy products in their natural forms are rich in fiber which fills you up before you get too many calories and slows the absorprtion, thereby reducing wide swings in blood sugar.
Optimal nutrition for losing weight is also lower in fat because fat is dense in calories: 9 calories/gram versus only 4 calories/gram for protein and carbs.
There is a convergence of dietary recommendations, as I describe in an essay I wrote a few years ago.
You have a spectrum of dietary choices, but some are more healthful than others. What you choose to eat is a very personal decision. I just want to make sure that you have the information you can use to make informed and intelligent choices.
So, to paraphrase Gertrude Stein, a calorie is a calorie is a calorie in its effect on your weight but not in its effect on your health.
More information is available at the nonprofit Preventive Medicine Research Institute site, www.pmri.org.
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