Among Americans, losing weight is the most common New Year’s resolution. At the dawn of 2016, well-meaning people around the country hit the gym, beginning their low-fat, low-calorie diets, only to fall off the wagon a few weeks in. According to Dr. David Ludwig, there’s a reason why a low-calorie diet is so hard to maintain—and it has a lot to do with America’s larger problem with diets in general—we’ve been stuck in a low-fat mode for too long, and it’s making us obese.
Dr. David Ludwig is a professor of pediatrics at Harvard Medical School and a professor of nutrition at the Harvard TH Chan school of public health. He joined Jim Braude and Margery Eagan on Boston Public Radio to discuss his new book on nutrition: Always Hungry: Conquer Cravings, Retrain Your Fat Cells, and Lose Weight Permanently.
“Research shows that high fat diets are much better than low-fat diets for quick weight loss,” Ludwig said, “but they’re not only good for your waist, they’re good for your heart.”
We all recall the original food guide pyramid, with up to 11 servings of grains at the base, and fat at the very top. According to Ludwig, the low-fat, low-calorie method Americans have been swearing by for the past 40 years is only making us hungrier. “We’ve been embracing this calorie-in, calorie-out model for 40 years, and where has it gotten us?” Ludwig said. “Basically the heaviest nation on the earth. We’re head-to-head [with Mexico] here, but this is not a race we want to win.”
With low-fat yo-yo dieting, Ludwig says we’re starving our bodies of the nutrition they need. “We know you can force calories out of the body by eating less,” Ludwig said, “But what happens? the body fights back. The first thing that happens is, we start to get hungry, and our metabolism begins to crash. The calorie-in, calorie-out model is a tried-and-true physical principle, it works very well for toaster ovens, but humans aren't machines. Our body adapts to the things that happen to it, and when we cut back on calories, we create a battle between mind and metabolism we’re destined to lose.”
According to Ludwig’s research, even when we’re stuffing our faces, our bodies are actually struggling to make the calories mean something. When we can’t get enough calories to our bloodstream, Ludwig says our fat cells go into something he calls “calorie storage overdrive.” This basically means our fat cells are working too hard to suck in the few calories we do get, the brain tells body it’s hungry, and the metabolism slows down to conserve supplies. “Then we eat more,” Ludwig said, “and we solve the problem temporarily, but if the underlying problem remains, these fat cells on calorie-storage overdrive, too much of the food we eat winds up in fat cells, and this becomes a never-ending vicious cycle.”
If we look back a few years, Ludwig says we’ve known all of this for a long time. “Research that dates back a century suggests that highly-processed carbohydrates—not that all low-fat diets are inherently bad—but the way we’ve done it, all of these highly-processed carbs, the fat-free, snackwell phenomenon, calorie-for-calorie, processed carbs raise insulin more than any other food,” Ludwig said. “Insulin is the 'Miracle-Gro' for your fat cells… just not the sort of miracle that you want.”
When our insulin levels go up, it triggers fat cells to suck in calories. “If someone with Type 1 (Juvenile) diabetes comes in, before they’ve been diagnosed, they haven’t had enough insulin, and they’re invariably losing weight. They can consume 5,000—10,000 calories a day, and they’re still losing weight. Give them insulin, they’ll regain the weight that they’ve lost, give them too much insulin, and they invariably gain weight, excessively,” Ludwig said. “For the rest of us, if you don’t have diabetes, you’re making your own insulin, it’s not being administered, you make more of it, calorie-for-calorie, with a highly-processed carb, low-fat diet, and that insulin programs the fat cells to take in too many calories, there are too few for the rest of the body, and that’s this battle between mind and metabolism.”
So how can we combat our culture’s trendy penchant for starvation?
“The fastest way to [reverse it] is actually with a higher-fat diet. It’s a lush, satisfying, savory diet, the way we ate in the 1950’s and 1960’s before the low-fat craze, with all of these lush fats it’s very easy to get rid of the processed carbs.”
Ludwig says that his proposed diet is similar to a mediterranean diet, and has been proven to turn off cravings in the brain. “We’re talking nuts and nut butters,” he said, “full-fat dairy, full-fat sauces and spreads, savory proteins, and natural carbohydrates. We don’t eliminate carbohydrates entirely, this isn’t an Atkins diet, but they’re slow-digesting carbohydrates that don’t raise insulin levels.”
In 2013, a study published in the New England Journal of Medicine put 7,500 adults at risk for heart disease put on a low-fat, controlled diet, or higher-fat diets with loads of nuts or olive oil. “They had to stop the study early,” Ludwig said, “because heart-disease rates dropped so fast in the higher-fat groups, it would have been unethical to keep the control group eating a low-fat diet.”
Of course, this full-fat theory goes against the messaging Americans have heard for decades. If you want to lose weight, eat less, move more, and cut down on fat. How could that be wrong? “It really makes sense, and it fits into our cultural notions of discipline, and in the short-term, it works,” Ludwig said. “It just disregards basic facts that we’ve known in the laboratory for decades, if not a century, that body weight is controlled just like any other biological function. You can lower the amount of carbon dioxide in your blood temporarily by breathing fast, but few people can do that for the long-term.”
If conscious control of calories were so important to weight control, how did humans ever manage to avoid massive swings in body weight before the very notion of calories was invented?
The U.S. Department of Health and Human Services and U.S. Department of Agriculture recently released their 2015-2020 dietary guidelines, which essentially say: don’t worry about cholesterol, eat less sugar, and don’t worry too much about meat unless you’re a growing teenage boy or man. Despite their wide audience, Ludwig says to take these guidelines with a grain of salt.
“Reducing sugar intake is probably the most important positive step with the new formal guidelines,” Ludwig said. “But many of their recommendations were ignored, this turned out to be a very political process, as it typically is… the USDA has multiple missions. One is public health, one is to support the commodities. Every commodity is lobbying not to have their products stigmatized.”
“My biggest concern is their number one recommendation, which is balance your calorie intake with your calorie output,” he said. “I really consider this a cultural delusion. If conscious control of calories were so important to weight control, how did humans ever manage to avoid massive swings in body weight before the very notion of calories was invented?”
Ludwig’s program was developed with other researchers and with the help of his wife, gourmet natural foods chef Dawn Ludwig, who oversaw the recipes and meal plans. It suggests quality sleep, stress relief, and enjoyable physical activities in addition to the diet plan.
So what are good carbohydrates?
“Largely the stuff your mom told you to eat, the whole foods,” Ludwig said. “Forget calories. Focus on the quality of what you eat. And let your body do the rest.”
“We want you not to cut calories,” Ludwig said. “Eat until you’re satisfied, snack when hungry, and forget calorie-counting. when you reverse this process of fat-cell calorie storage overdrive, your body lets calories back into your bloodstream, your brain senses better access to needed fuels. For some people, for the first time in years, hunger decreases, cravings turn off, and your body wants to shed the excess weight.”
Typical day in Phase One (of three total phases):
Breakfast:
Huevos Rancheros, substitute tortilla with a side of full-fat yogurt and berries
Morning snack:
Herb-roasted chickpeas
Lunch:
Steak salad with real blue-cheese dressing
Vegetarians: Substitute tofu or tempeh for steak
Afternoon snack:
Apple and almond butter
Dinner:
Coconut curry shrimp on a bed of spinach
Dessert:
Fresh berries with real dark chocolate and real whipped cream
Dr. David Ludwig is a professor of pediatrics at Harvard Medical School and a professor of nutrition at the Harvard TH Chan school of public health. To hear more from his interview with BPR, click on the audio link above.
