By Mia Zaharna, M.D. and Henry I. Miller, M.D.
Many New Year’s resolutions involved a new gym membership or at least a commitment to break a sweat frequently, most often in order to lose weight. Manufacturers of exercise equipment and the mainstream media have tried to convince us that the “no pain, no gain” mantra–a la “The Biggest Loser”–is the key to shedding pounds, so that to slim down we need to wear a Fitbit, walk the equivalent of a marathon every day and maybe even get a treadmill desk.
But you might want to think twice before you toss out your comfy office chair.
Recent research has shown that exercise is in fact not the key to weight loss, and in some cases, may even lead to weight gain. Although exercise is certainly beneficial to health by reducing the risk of a range of diseases such as coronary heart disease, various cancers, stroke and type 2 diabetes, as well as reducing symptoms of depression and anxiety, unless you’re a tri-athlete, in most cases exercise alone will not lead to significant weight loss.
A large study published last year by an international group of academics showed that exercise had only a weak influence on overall calories burned–and exercising harder didn’t equate to burning more calories. Other studies (here, here, here, here and here, for example) have shown that people tend to eat more calories when exercising, and the calories consumed are not offset by those burned by the exercise. An example is Dr. Oz’s breakfast smoothie (as recommended in his Rapid Weight Loss Plan), which has 350 calories. It would take the average 150 lb person about an hour of brisk walking to burn this off. Eat a normal lunch and dinner, and you might need to walk all day. Uphill.
Diet has more influence on weight loss. Multiple studies (here and here, for example) have confirmed that whether it’s a high protein, vegetarian, vegan, junk food, juice or cabbage soup diet, what matters most is total calories consumed. According to the dietary guidelines on Health.gov, when it comes to calories and managing your weight, where the calories come from doesn’t matter; for the most part, a calorie is a calorie is a calorie.
Although there is no doubt that eating a healthy, well balanced diet has benefits beyond just weight loss, paradoxically a pop tart might be just as good for losing weight as a bowl of quinoa and green juice. In fact, a Kansas State University nutrition professor ate only “convenience store snacks”–including a smorgasbord of Twinkies, Little Debbie confections, Doritos, and Oreos–and lost 27 lbs over ten weeks. The key was that he dropped his caloric intake from his normal total intake of 2600 per day to 1800. Unexpectedly, not only did he shed the weight, but reportedly his bad cholesterol and triglycerides dropped and his “good” cholesterol increased significantly. (We not recommend that you try this at home, however.)
On the other hand, a 2011 study conducted by nutritionists at Harvard University and published in the New England Journal of Medicine showed just the opposite–that in fact there may be “good” calories and “bad” calories. The study examined the dietary and lifestyle habits of more than 120,00 U.S. citizens from 1986 to 2006 and concluded that calorie for calorie, foods such as potato chips, potatoes, sugar-sweetened drinks and both unprocessed and processed meats contributed more to weight gain than other food types such as vegetables, whole grains, fruits, nuts and yogurt. However, those findings seem to be contradicted by the joint 2013 statement from the American Heart Association, the American College of Cardiology and the Obesity Society, which said about overweight and obese adults, “to achieve weight loss, an energy deficit is required.” In other words, what’s necessary for weight loss is fewer calories, regardless of where those calories came from.
Where does this stew of research findings leave us? Certainly, decreasing calories is essential, but whether those calories should come from a candy bar or a handful of nuts is less clear.
Our advice is to avoid trendy diets. There’s no magic in them, the results seldom last, and they can be expensive. Last year gave us Paleo, raw food, juicing, “clean eating” and, in stark contrast, the “poop diet.” (We are not making this up.) And while any of those diets may result in weight loss, it’s likely due to restricted calories rather than the result of flushing toxins from the body or some other mumbo-jumbo justification that owes more to slick advertising than to physiology. De-tox? Your liver and kidneys are remarkably skilled at removing toxins from your body on their own. That’s what they do, all day, every day.
Our local mall just replaced Auntie Anne’s Pretzel shop with a Pressed Juicery, which offers a five-day juice detox cleanse for a mere $229. Never mind that one small bottle of many of their signature juices contains more calories than a hot buttery Auntie Anne’s pretzel.
Bottom line: If you’re resolved to lose weight, cut calories in whatever way best suits your appetite and wallet. Adopting the mantra of “calories in versus calories out” will get you there.
Mia Zaharna is a psychiatrist specializing in sleep disorders. Henry I. Miller, a physician and molecular biologist, is the Robert Wesson Fellow in Scientific Philosophy and Public Policy at Stanford University’s Hoover Institution. He was the founding director of the FDA’s Office of Biotechnology. Twitter: @henryimiller.