Recently, The New York Times, CNN, and other news media reported the findings of a new study about weight loss. The study, which was financed by the National Institutes of Health, conducted by Tulane University, and published in the Annals of Internal Medicine, reported that obese subjects lost more weight by limiting carbohydrates and eating more fat (while those on a low fat, high carb diet lost less weight). How can this be? These findings contradict the traditional dieting wisdom, which advocates a low fat diet.
First, remember that the media gives high visibility to provocative news, right or wrong. Also, upon review, the study has serious design issues that undermine its controversial findings. Equally important, this study’s results conflict with my own knowledge and experience of what works with my clients for gradual, permanent weight loss and maximum health.
Therefore, I wanted to make you aware of some important points the news stories didn’t report that could make a big difference to your health and your weight. That’s why I’m recommending you ignore this study and go for the carbs! (And I’m talking about complex carbs like whole grains, fresh vegetables, beans and fruit—not unhealthy, refined carbs like sugar, sweets and white flour).
• The difference in weight loss over the course of the year was only 7 pounds. Those on the low fat diet lost about 4 pounds, while those on the low carb diet lost about 11 pounds. According to experts, participants on the low carb diet lost more weight because they ate fewer calories than the subjects on the low fat diet. In one commentary, David L. Katz, MD, MPH, director of Yale University Prevention Research Center, wrote: “This was not a study of low-carb versus low-fat diets. The study compared a low-carb diet with a minimally fat-reduced diet. The much more restrictive low-carb diet wound up being considerably lower in calories throughout the study – and for that reason participants in that group lost more weight.”
Another doctor, Peter T. Ostrow, MD, PhD, Co-director of the Research Center for Stroke and Heart Disease, and associate professor of pathology and neurology at the University at Buffalo, elaborates: “Those on a low-fat diet reportedly consumed an average of 1,527 calories per day, while those on a low-carbohydrate diet took in an average of 1,448 calories. That’s 79 calories a day less, which… over a year becomes a total of almost 29,000 calories. If we use the standard that 3,500 calories equals 1 pound, the people on the low-carb diet would have an additional weight loss greater than 8 lbs. That means the additional weight loss could be accounted for entirely by caloric intake, without regard for fat or carbohydrates.”
• Equally important, our bodies run on carbs. Depending on which source you consult, we need anywhere from 3 to 7 times more carbs than protein. Our bodies use carbs to power every thought we think and every move we make. If we deprive our body of its preferred fuel, the body must instead burn protein and fat. That’s like running a Porsche on crude oil. The engine may run, but you’ll gunk up the mechanism—in this case, your kidneys, liver, and gall bladder, and you’re at increased risk for diseases like cancer, gout and diabetes.
• Here’s something else the media didn’t report: Since our bodies require more carbs than protein or fat, we naturally crave carbohydrates. The subjects in the study assigned to follow the high fat diet had a hard time restricting carbs, and by the end of the study, they were cheating regularly. They just couldn’t stomach the lack of carbs on a long-term basis.
• But what about fat? Is a high fat diet really healthy, as claimed by the reports on this study? As any overweight person can tell you, our bodies can make fat all by themselves. We can survive for weeks without eating extra fat. Yes, fat is essential for many body functions, but a little goes a long way. There’s certainly no need to follow a high fat diet for good health. Dr. Katz agrees: “All of the participants were obese at baseline and had impaired cardiac risk measures because of obesity – so those who lost more weight had more improvement in cardiac risk for that reason.”
• Another important point: the study didn’t distinguish between unhealthy, refined carbs such as sugar and high fructose corn syrup, and healthy, complex carbs such as whole grains, fresh vegetables and fruits. There’s a big difference between a bowl of cookies and a bowl of oatmeal. Junk carbs like sugar are a big problem and do contribute to weight gain and poor health. High quality carbs like brown rice, barley, millet and oats contain valuable B vitamins, antioxidants, fiber and other vital nutrients that protect our bodies from disease, curb our hunger, and lead to healthy weight over time.
• Likewise, the study did not distinguish between healthy fats like seeds and nuts, and unhealthy fats like bacon, cheese, lard and shortening. In his commentary, Dr. Katz wrote: ” The wholesale cutting of these macronutrient classes without regard for the foods involved is discredited nonsense. Cutting ‘carbs’ would mean cutting vegetables and fruits; cutting ‘fat’ would mean cutting nuts, seeds, and avocado. These are not sensible practices.”
• Another problem with the study—the subjects were discouraged from exercising. According to Sonya Angelone, MS, RDN, and a spokesperson for the Academy of Nutrition and Dietetics who was quoted in the Annals of Internal Medicine article: “Muscles use carbohydrates as fuel. It can be hard to exercise on a low-carb diet.” In other words, if the high carb eaters had been allowed to exercise, it’s likely they could have exercised longer and harder than the high fat eaters.
• The high fat diet in the study relied heavily on meat and other animal foods. But diets high in animal protein are linked to kidney damage, cancer, and digestive disorders. Every major dietary study has shown that the less animal food we consume, the lower the incidence of disease and the longer our lifespan. However, the results are not always apparent within a single year.
• Another problem: When we eat lots of protein and avoid complex carbohydrates like whole grains, we end up changing the microbiota of our intestines. According to the Journal of The Academy of Nutrition and Dietetics (September 2012, Volume 112, Number 9), whole grains contain important elements, “such as oligofructose and inulin, (which) are beneficial for creating a healthy composition of gut bacteria.” Why is this important? Two reasons:
1. Two-third of our body’s serotonin is manufactured in the intestines. When our microbiota is compromised, we produce less serotonin, also known as “the happiness hormone.” Without enough, we feel anxious and depressed. In addition, serotonin is necessary in order to produce melatonin, which helps us sleep. In other words, if we don’t have the right microbes in our gut, we can’t sleep as well at night. Without enough sleep, we can’t heal and repair cells, think clearly the next day, and we age more quickly. In short, healthy carbs like whole grains make us happy, help us sleep, and keep us young.
2. As far as weight loss, scientists have recently discovered that overweight people have an altered gut microbiome. So even if a high fat, high protein diet did lead to short-term weight loss (which the study did not prove because of its poor design), in the long term such a diet will alter the microbes of a person’s digestive tract, setting him or her up for future weight gain.
For all these reasons, I’m recommending you take this latest weight loss study with a huge grain of salt. If you base your diet around whole grains, fresh vegetables, beans, nuts, seeds, and fruit, you’ll live longer, avoid illness, lose weight gradually (if you need to), and feel great.
For the actual study, click here.
For a good report on the study published by the National Institutes of Health, click here.
For a lively and informative critique of the study, click here.
For a more thorough critique of the study and mainstream media reporting by several doctors, including the two quoted in this blog, click here.