The Clean Plates Interview: Dr. David Ludwig
Published on October 4, 2016
Last updated August 16, 2018
By Beth Lipton
No matter how convincing a diet “guru” is these days, you don’t have to look far to find another shouting just as loudly with the opposite information. For those of us who just want to look and feel good, it can be difficult to know what—and whom—to believe.
Safe to say, Dr. David Ludwig is not your typical Instagram “lifestyle expert.” Considered one of the top nutrition experts in the world, he’s a Harvard professor of both pediatrics and nutrition, the director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital, and a practicing endocrinologist who’s published more than 150 scientific articles, in addition to the recent Always Hungry?: Conquer Cravings, Retrain Your Fat Cells, and Lose Weight Permanently.
Dr. Ludwig talked with Clean Plates recently about why conventional diet wisdom is the opposite of good advice, how to get to a healthy weight without suffering or deprivation, and why dark chocolate is a health food.
Clean Plates: What’s wrong with the conventional wisdom that tells us the key to good health is to eat less and move more?
Ludwig: The conventional approach is based on the notion that all calories are alike, and so one has to simply eat less and move more: Establish a negative calorie balance and you will lose weight. If you can cut calories, you begin to lose weight—and most people can, for the short term. But over the long term, very few people, less than 1 in 10, can keep that up.
According to the conventional view, that’s a personal failing. People see it as a lack of discipline, sometimes even a character issue. People with weight issues so often experience stigma, bias, and even abuse, for having this particular medical problem, unlike virtually any other medical problem.
The obvious problem with the calorie in, calorie out model is it disregards a fundamental scientific fact that has been established in the laboratory for almost a century, which is that body weight is more about biology than will power, at least over the long term.
When we lose weight by restricting calories, predictable biological responses will kick in. The body fights back with rising hunger, slowing metabolism, and the mounting of a stress response—the secretion of stress hormones, which take a toll on the body. This combination of increasing hunger and slowing metabolic rate is a recipe for disaster, and yet the conventional mindset tells us to just ignore it, and presumably, I don’t know, just be hungry for the rest of your life? It’s an impossible task for most people, if you simply cut calories and you don’t change the quality of what you’re eating.
CP: What are the most common mistakes you see people making in what they eat?
Ludwig: The low-fat paradigm is entrenched in our consciousness, which is not surprising. The food pyramid had fat at the apex and a range of carbohydrates at the base. After being told for 40 years that if you eat fat you’ll get fat, and it will clog up your arteries, people are afraid of that.
There’s no scientific basis for that, and in fact, the opposite is true. In the studies where [researchers] can effectively get people to change their diets, the meta-analyses show that a low-fat diet is about the worst approach to weight loss, compared to virtually every other high-fat diet. And even more importantly, these higher fat diets are not only good for your waist, they’re better for your heart—opposite of what we were told.
The PREDIMED Study in Spain, one of the largest studies of heart disease done, gave adults who were at risk for heart disease either a standard low-fat diet, or one of two higher-fat diets, Mediterranean diets. One was enriched with olive oil—they gave them a liter a week per person. That’s a lot of olive oil. That would be a nightmare from the low-fat perspective. Another group got an ounce of nuts a day. They had to end the study early when an interim analysis by independent experts found that cardiovascular disease rates dropped so fast in the high-fat groups, the study was proven years before expected. And it would have been unethical to keep the low-fat group eating that diet.
This obsessive focus on reducing dietary fat caused more harm than good. The high-fat foods that were banished from our plates—olive oil, some kinds of nuts, full-fat unsweetened yogurt, dark chocolate—these are among the healthiest foods you can eat. Some people are now going to the other extreme and saying saturated fat is a health food, and I say, the truth is in the middle. Not all saturated fats are the same. But saturated fat in whole foods is fine.
But that doesn’t mean [you should] go out and bathe in butter, either. Focus on whole foods, and then for your added fats, some butter is ok, and then let’s emphasize olive oil and be sure to get a good balance of Omega-3 and Omega-6 polys and I think we’re in good shape.
CP: Your book, Always Hungry?, promises weight loss without deprivation, and without extreme exercise. How is that possible?
Ludwig: Our approach is based on trying to understand the biological drivers of weight gain. We’re not programmed to weigh more and more every year, every generation, as has happened in the United States, overlapping with the [emphasis on] low-fat diet. It seems implausible that we’ve suddenly lost self-control, that our moral fabric is unwinding, and we’re giving in to gluttony. We know that biology is driving this. We can demonstrate that in the laboratory.
People’s metabolic rate drops with calorie restriction—so the body is fighting back. Why? The research suggests that the underlying problem is that fat cells go into calorie-storage overdrive. For some reason, they’re taking in and holding on to too many calories. So there are actually too few for the rest of the body. The brain can’t see that there are too many calories in the fat cells, it just sees that there aren’t enough in the bloodstream.
If you can cause fat cells to stop storing too many calories, then there will be more available for the rest of the body. The brain will sense that, and hunger will spontaneously decrease, cravings will decrease, metabolism will speed up. Those are predictable responses.
So if we want to take advantage of those built-in biological responses, we have to address the underlying drivers of weight gain, and that’s fat cells that are on calorie storage overdrive, driven mainly by too much insulin—you can think of insulin as MiracleGro for your fat cells.
If you don’t have diabetes, the fastest way to change your insulin levels is to look at the amount and type of carbohydrates that you’re eating. Cut back on the processed carbs that have flooded into our diet over the last 40 years with the low-fat craze, and within one day, insulin levels will drop. And as those insulin levels drop, your fat cells begin to release some of those pent-up calories back into the bloodstream. The brain likes it, hunger turns off, metabolism speeds up and you begin to lose weight with the body’s cooperation, not with your body kicking and screaming. This may not be as fast as a severely calorie-restricting diet, but it’s one that aims to get the body into a sustainable weight loss state without restricting calories.
CP: You mentioned insulin. As an endocrinologist, you deal with people’s hormones. What can we eat to keep our endocrine systems functioning best? How does that affect overall health?
Ludwig: If you put someone on a desert island with nothing to eat and you come back in a week, you’ll notice three things: Their hunger has become ravenous, their metabolism has slowed down, and their body is secreting stress hormones. What the stress hormones do is try to scavenge calories from other types of tissue. They try to get them out of fat cells. But if the fat cells are being locked down, then they’ll also take calories out of lean tissue, such as muscle.
That’s why when people lose weight, they can lose weight in very different ways. Some people can lose weight virtually 100% from fat, so they have as much lean tissue—as much muscle and organ mass—after weight loss as they did before. Other people lose a great deal of muscle as they’re losing weight. If you lose muscle mass, you’re going to be weak. Your metabolism will slow down. You’ll be less able to engage in physical activity. That’s a recipe for weight gain, and increased cardiovascular risk.
So it’s where those calories come from that’s key. If you’re eating a diet that’s raising your insulin levels, and your body can’t get the fat, it’s going to try to get those needed calories from lean tissue. That might look good on the scale, but you won’t look or feel good. The key is controlling insulin.
CP: So we know what not to do. How does the program in your book work, specifically?
Ludwig: The program is 3 phases. Phase 1 is just 2 weeks, and we call it a boot camp for your fat cells, not for you. It’s designed to jumpstart change in metabolism as quickly as possible. You lower carbohydrate down to 25%. You’re still having plenty of fruits, non-starchy vegetables, and beans. But you give up grains, potatoes and added sugar for those 2 weeks. We find that people remarkably lose their cravings for these things, because they’re replacing those calories with luscious, very satiating high-fat foods. Nuts and nut butters, full-fat dairy, rich sauces and spreads, avocado, real dark chocolate.
In phase 2 you add unprocessed or minimally processed whole-kernel grains: wheatberries, steel-cut oats, brown rice, whole barley, quinoa. We still have you stay off of white potato, and just have a very small amount of sugar, 3 teaspoons maximum of added sugar [per day]. You stay at phase 2, which is still a relatively high-fat diet with a little extra protein, until your weight comes down to a new set point. When you stabilize at this lower level will vary from person to person. Some people have 10 or 15 pounds to lose, others have 75 or 100 pounds. So it’s going to happen at different rates. But when you stabilize there, you go on to phase 3, where you start adding back a little bit of processed carbs to see how much your body can handle.
It’s not an extremist approach. We don’t say you have to get rid of all carbohydrates or even get rid of treats for the rest of your life. Our motto is, ‘Maximum results through minimum deprivation.’ So if you can tolerate a little pastry, pasta, ice cream, after you’ve improved your metabolism from phases 1 and 2, we show you how you can incorporate that. We also bring in three other things, we call them life supports, throughout the program: Stress relief, quality sleep and enjoyable physical activities.
Our mantra is, ‘Forget calories, focus on food quality and let your body do the rest.’