Dr. Roberts Lecture: Weight loss that works without gimmicks

Weight loss without gimmicks, or Weight loss that works!

Obesity today is a problem that’s completely out of our control. This is an enhanced transcript of the talk that Dr. Roberts gave in Boston at the Human Nutrition Center on Aging, Tufts University. Dr. Roberts brings scientific rigor and common sense to the weight loss conversation. 

Don’t worry, the sound improves dramatically once Dr. Roberts takes the podium at 1:40 in the video. 

The emotional and economic cost of obesity

Two thirds of us in America are overweight. And the rate of childhood obesity continues at horrible proportions. In any one year, 51 percent of adults attempt to lose weight. Americans are very unhappy with their weight. If you ask an extremely obese person whether they would rather be obese or blind or deaf or have diabetes, predictably they would have anything rather than be obese. They would rather be deaf, they would rather be blind, they would rather have diabetes. This is an enormous problem. People are suffering from this and it’s a very expensive problem. The cost of Medicare and Medicaid and estimated lost productivity from obesity comes in at about $90 billion or so a year — and those are actually the figures from a few years ago. Consumers spend an additional $35 billion. If we were to solve the obesity problem, you could significantly change our country’s economics. This is big money that we’re talking about.

Food supply driving obesity

How did we get here? We’re going to talk about how to deal with it, but let’s just start off with food. The USDA has a per capita food consumption corrected for waste – back in 1975 our food supply was 2100-2200 calories per person/day. Today our estimated food supply is 464 calories per day more than it was in 1975. That’s a huge amount. That’s a whole meal. And you don’t have to go much further than to see why are we fat. We are fat because we are eating more. And I’ll go back to the underlying reasons for that. But food is the major problem.

Corn syrup and low-grade food oils

What have we eaten? This information is from the USDA. Two foods account for most of this increase. High fructose corn syrup, and oil. Four more things contribute a bit more: flour, cheese, shortening and edible beef tallow. What didn’t increase was all the good stuff: Beef, seafood, candy, chocolate, chips and cream have all been flat. Ice cream and frozen dessert consumption actually decreased 13 percent. This isn’t high living that’s made us fat. This is high fructose corn syrup and oil. We haven’t been going out eating and indulging in wonderful food to do this to ourselves.

Exercise vs calories

I’m going to talk about the theory of weight control and then talk about where we need to go from here. If we expend an average 2200-2300 calories — as long as what we eat equals what we expend, we maintain weight and everything is good. If we want to lose weight, there are a few ways we can classically consider it. We can increase our energy expenditure – there has been a lot of government advice on increasing energy expenditure (exercise) – or we can reduce energy intake. So energy expenditure – the trouble with increasing energy expenditure (exercise) is it doesn’t work.

You can’t outrun calories

There have been about 50 exercise intervention studies that have looked at how much body fat changes when you introduce exercise for the long term, and this line here [slides] is the slope of the relation between exercise and body fat, the same slope for women and men. One hour a day of exercise, that’s about the absolute most you can get anybody to do in an exercise intervention study, and that’s a huge thing. It’s very hard to get anybody to add an extra hour a day. Most of these studies only manage to get people to add about half an hour.

If the whole population added one hour a day of jogging, vigorous exercise, that would result on average of about a six pound decrease in weight [in a year] — not very much. And speaking on a population level, that’s completely unfeasible. You can’t get the whole population to add a whole hour a day of exercise. That would be a major change in lifestyle, work product, everything. So when we think about changing obesity in the country, we have to focus more on food.

Fasting is cruel and ineffective

It’s quite instructive to think about what starvation would do. We would never recommend starvation. Starvation is very harmful and kills people. If you starve somebody, the most fat they would lose would be about four pounds a week because energy expenditure (metabolism) drops during starvation (fasting), and this difference between intake and expenditure are multiplied by the energy cost of fat over the week, it’s only four pounds a week. So what if you just cut calories in half? That’s also a pretty serious thing to do. Energy expenditure doesn’t drop so much. The difference between consumed and expenditure adds up to about two pounds loss of fat per week; perhaps a bit more, but only about two pounds. And again, this is serious stuff, asking people to cut their calorie intake in half. The famous Minnesota Starvation Study from World War II cut calories in half and they got a whole buffet of symptoms, raging hunger, lethargy, cravings, loss of sexual function – lots of impulsive behaviors. It was very bad for the subjects’ health.

Two pounds per week

So where does this lead us? Two pounds of adipose tissue per week are about the maximum sustainable weight loss we can get out of people. We do better now than back in World War II in terms of how to get people to cut calories and feel okay about that. But two pounds is about the limit. Diets promising more are making false claims, it’s a simple as that. If you look on Google I’ll show you that there’s many false claims. Even two pounds a week is a serious diet. You can’t just do that by cutting calories because if you cut calories you’re back in the Minnesota starvation experiment. People get starving and have symptoms and can’t keep it up.

False diet claims are rampant

And the implication of this is that losing significant amounts of fat is a long-term project. That may not be enormous news to anybody in this building, because my guess is you’re more clued-in than the average American. But still today out there – oftentimes what people are doing is linking together a false claim and a gimmick. So they say “this is a special composition. All you have to do is eat avocados and you will lose 30 pounds a month”. You know, gimmicks and false claims are first cousins.

Maintenance after weight loss

After somebody has lost weight they have to keep it off. And people also get stuck there. So this [slides] shows where we were before we gained weight. In order to gain weight people are consuming more calories than they are expending. Once they have gained weight they continue to eat more to maintain that weight, because just walking around in a heavier body takes more calories. So you eat more, you gain weight, and then you need that amount of calories to keep your weight up.

We get somebody to lose weight, and then after weight loss, energy expenditure is reduced because you have a smaller body; it costs less calories to walk a smaller body around. And the implication is that you need to permanently eat less. Exercise does help a bit and you can keep energy expenditure up by exercising. But exercise isn’t enough. For people to lose weight and keep it off requires a permanent change in calorie intake.

Most diets create a rebound

In the lab we have made enormous strides in improving how we have helped people with weight. This is just one example from the Roberts lab. Back in 1994 we did a weight loss study. We successfully introduced a small amount of weight loss. This was a calorie cutting World War II kind of experiment. And subsequently our volunteers gained back all the weight lost and then some. They were ravenously hungry just from cutting calories. When we let them off the protocol that hunger was enormous and they would eat 5000 calories a day and still feel empty and they ended up fatter — significantly fatter than they ever had been in the first place.

Dieting without hunger or rebound

Today we can get people to lose far more weight using different kinds of diets and they can keep most of that weight loss off for the duration of the follow-up. So in the lab, there have been enormous advances in how to help people control weight.

False claims and the FTC

Out in the community it’s still the Wild West. The Federal Trade Commission is fighting an ongoing battle against false claims. These [slides] are the media recommendations from 2003, and I actually couldn’t find anything more recent than that, but they are arguing that none of the following claims should be out there:

Samples of actual false claims:

  • A weight loss of more than two pounds a week without diet or exercise
  • causes substantial weight loss no matter how much the consumer eats
  • causes permanent weight loss even when the consumer stops consuming the product
  • blocks fat absorption safely
  • allows you to lose more than three pounds a week for four weeks
  • causes substantial weight loss for all users
  • causes substantial weight loss by wearing it on the body or rubbing it on the skin.

I did a Google search last week when I was putting this talk together. I just typed in “how to lose weight”. And I came up with this [slides]. Every one of these things that come up on the front of Google is a false claim according to the definitions of the Federal Trade Commission:

  • “It’s foolproof.”
  • “Safely lose 20-30 pounds per month.“
  • “You can lose 30 pounds in 30 days.”
  • “How to lose 20 pounds of fat in 30 days.”
  • “I lost five pounds per week by obeying this one rule.”

The Federal Trade Commission war against false claims is not working. I will put that out there. I’ve got no idea how to fix that, but it’s not working and it’s extremely harmful because it gives the impression that weight loss can be easy and quick. And then when people find it’s not easy and quick, they’re more likely to give up.

So what should we be doing?

Just cutting calories doesn’t work. People are desperate to lose weight and that desperation is allowing advertisements out there to exist because people would like these false claims to be true. They have an enormous weight loss problem and they would like to deal with it. So I would like to spend a couple of minutes talking about why we eat the way we do as a means for what we can do going forward.h thank you,” when in fact what you should say is, “Look, this is a different result from somebody last year, and we need to weigh up the whole lot.”

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Scientific facts

There are a few things that all these studies agree on. Nutrition is a very controversial subject. You can easily find one study that says A and another one that says B, about all kinds of topics. But in the obesity field there’s four topics on which approximately 100 percent of studies all say the same thing. One is that we need to satisfy hunger. People who are hungry eat. And there appears to be at least four dietary factors that are specific for hunger. That is to say if you feed people these foods, they are relatively more satiating than junk food. High fiber foods work very well, for satiety and hunger control. Low glycemic index carbohydrates work very well too, particularly for people with high insulin secretion. High protein foods are also very satiating.

Fiber may be particularly important.

The average American today consumes about 15 grams of fiber a day. The national recommendation from the Institute of Medicine for fiber intake is 25 grams a day in women and 35 grams a day in men. This average of 15 grams is the biggest deficiency compared to recommendations of any nutrient on the spectrum. The American diet is astonishingly lacking in fiber by comparison with our recommendations, and when you compare it to the Paleolithic estimated intake of 100 plus grams per day, we are consuming only one-seventh of the intake that our Paleolithic genes have evolved to consume. Fiber is at the top of the list here because it’s probably the thing that has the most effect in terms of making hunger control easier in the population.

Liquid calories

I think there’s a special place in hell reserved for people who sell soda. Liquid calories have the opposite effect of fiber. They have literally no satiety despite high calories. There’s a whole bunch of studies from different labs — not mine — showing that if you give somebody a soda in the mid-morning, for example, they eat just as much lunch as if they had water. Our bodies don’t seem to register the calories in soda and in other carbonated beverages. And so you drink those calories on top of all the other food that you eat. Remember as well that one of the key major changes in the American diet has been a huge increase in high fructose corn syrup.

Excessive food supply

The second thing that everybody else agrees on is that we eat just because it’s there. This [slides] is just one study to give an example of this – bad popcorn in a big bucket. Moviegoers were given free popcorn – fresh or stale, medium or large. The stale had actually been aged for two weeks – they made it and then left it sitting around for two weeks. So it was really stale. So if you have a large portion of fresh popcorn, you eat more. If you have a large portion of stale popcorn, you also eat more. Just the fact that things come in large portions and it’s more physically available means that we eat more. I’ll go into the mechanisms underlying this in a minute.

Caloric foods

We also like calories. 75 percent of the foods that people say they like extremely or crave are the highest calorie things out there – chocolate, salty snacks, ice cream, brownies, cookies, cakes, muffins. That’s in America – if you go somewhere like China, which we’ve also done, you find that things like fried pork belly are at the top of their list, and these are also the highest calorie things out there. The energy density of foods is the factor. It’s not the taste of the foods, it’s how many calories they have. We have learned to like the taste of things if they have high calories. Which is why things like mashed potato taste good. Mashed potato tastes of very little but it’s packed with butter and cream, and our brain is smart enough to know that we get a rush of calories from it.


We also eat more with variety – variety is an enormously neglected factor in food regulation. Every single study that has ever been done shows that more variety leads to more consumption. That’s not just in humans, it’s true in rabbits, cats, trout, fruit flies – every kind of species that’s been studied; and there’s been something like 10 or 15 species. If you put more variety in front of a person or an animal, they consume more. We are so sensitive to variety, that even if I do something like put three shapes of pasta on your plate rather than one shape, you increase the pasta consumption by 14 percent.

That’s important because there’s been an explosion in variety in the American food supply. Starting in about 1980, this [slides] is how the variety of candy and gum went up, also bakery foods and entrees. Fruits and vegetables haven’t enormously increased in variety because we are limited by what fruits and vegetables grow. And it’s worth noting that it’s a break point in obesity. Sometime around 1980 was when we actually lost control. And that break point also coincides with the break point in increasing junk food variety.

Feeding centers in the brain

So there’s four things that humans seems to be hard wired to eat for. We eat for hunger, we eat because the food is there, we eat variety more. So what’s going on? In the brain we know that eating is controlled by three distinct neurological systems. We have the hunger/satiety center, we have a pleasure center in the front of the cortex, we have a reward center in the midbrain. This section here [slides] is our unconscious brain. Hunger operates out of our unconscious brain. Reward operates out of our unconscious brain. The only thing that we’re actually conscious of is the pleasure, but the need, the addiction chemicals like dopamine that we get from eating happens down here in our unconscious brain. And so does hunger. And I’ll explain why that’s important in a minute.

Hunger is beyond conscious control

So our unconscious brain receives the signals that keep it happy or tell us that we need to eat. We have afferent signals coming up from our body. What we eat determines – nerve signals from the stomach, gut hormones, circulating nutrients and fat cells — all of these tell our hypothalamus, they tell our midbrain, the state of food in the body. Have we got enough food, do we need to eat more?

Our environment manipulates us

That’s our internal control. We also have a whole system of external control. Our senses –- sight, smell and taste – report what’s out there to our hunger satiety and reward and pleasure centers. And they do that through what’s called the cephalic phase of digestion. When we have a large pizza in front of us, for example, the sight, the smell and if we are silly enough to have the first bite, the taste of that pizza activates a whole chain of metabolic events. It increases real metabolic hunger by decreasing blood glucose. Blood glucose changes is one of our signals for hunger. A bunch of studies have shown that. So you see pizza, you have a surge of insulin, it drops blood glucose and you’re actually hungry. You need to eat, because even if you have enough nutrients in your body, you’re getting the signals that you are actually hungry and in need of food.

That same sight of the pizza also expands stomach volume. And that means that you have a bigger stomach, which needs more filling to feel equally full. That’s a very important concept. You look at the pizza, the pizza looks nice, your stomach muscles relax and you need to put more in your stomach before you get signals saying I’ve eaten enough. It also accelerates digestion. Gastric motility is increased, so that you put that pizza away more quickly and you’re ready for the next meal again. That’s something called the second meal effect, when you have something good you actually digest food faster and you’re ready for another go.

What this all means – and this is my most important slide. If you’ve been asleep, please wake up now.

The environment controls our metabolism

In effect, the environment controls our metabolism. We are hard wired to have our food intake controlled by what’s in front of us. It controls our hunger, it controls our synthesis of addiction chemicals that keeps us eating. And when there is more food in front of us, we need to eat more to feel equally satisfied. That’s a huge, important thing. And what this does, it explains why an increasingly toxic environment made us eat 556 calories more of something which none of us would consider delicious; high fructose corn syrup and oil; simply because it was in front of us, it was available, and some of it was liquid calories which our body doesn’t even see. We ate those things to feel equally full. Nobody was being indulgent here – everybody feels guilty today, but in fact nobody was being indulgent. People feel guilty, but we overeat to feel normal because of this environmental control over hunger and metabolism, which happens unconsciously.

Modern commercial culture makes obesity inevitable

The big picture is that bad food environments make weight control literally impossible, even for people with good intentions. That’s something that needs to be on the table more than it is.

Taking action

So to come back to the purpose of my talk, avoiding gimmicks is important. I don’t want anybody in America to believe that you can lose 30 pounds of fat in 30 days because you really can’t. But avoiding gimmicks is not enough. To lose weight and keep it off, individuals need to do things. They do need to have realistic expectations about how much weight they can lose, there’s no magic belly fat solution; and that they need to reduce their energy intake for a long time in order to become non-obese.

They need to eat foods that satisfy our basic hardwired biology, all of these afferent signals coming up from our vagus nerve from circulating nutrients and practice – that means high fiber foods, high protein foods, high volume foods, and low GI carbs. They need to satisfy variety instincts with more high satiety variety. Not the brownies, chips, cookies, which are very easy to get because there is such an abundance of them in the supermarket. And they need to satisfy their caloric density instinct with more regular meal structure and various other things that will help that. And they need to reduce metabolic stimulation from excess food in their own environment. They need to get rid of the sight, the smell, the general availability of food.

Take charge, take responsibility

That’s a hard thing to do in our country. Society needs to help, I think, and it’s something that’s not happening. Consumers can do more to help themselves. They can take charge, make their work environment better. As parents, they can get involved in school food. The media can do a great deal more. They can refuse advertising for untested gimmicks and diets that promise too much. Some outlets do that already, but others don’t. There are a large number of magazines, for example, and ways to get around the FTC guidelines that even the major TV channels do today, just because people are so obsessed with weight loss and are so unhappy about it. They want to do that.

Scientists, I don’t think progress is over yet. We’re doing a lot better, but there’s more progress we can make on how to make things easier, and to be responsible when talking to the media. The media comes along and says, “Oh, wow, what a fantastic study, Dr. Roberts.” It’s easy to say “Oh thank you,” when in fact what you should say is, “Look, this is a different result from somebody last year, and we need to weigh up the whole lot.”

Change the food environment

I’ve reserved the biggest number of bullet points for the government, because I think that’s where the most work needs to be done right now. I think it would be really helpful if you guys went and spread the word more about that the obesity crisis. It simply will not be solved without a great deal more Federal government involvement.

We need to get economists and nutritionists and scientists to work out how to change the food environment. The key thing here is that introducing healthy choices will not be enough, because unhealthy food speaks to our unconscious brain, and unhealthy food has to be disappeared in some way in order for the obesity crisis to really be solved.

Think big

And what’s wrong with thinking big? We’re not just talking about regulating school food here, because that won’t be enough. Restaurants are a big problem. Restaurants typically provide portions that are two to three sizes what somebody actually needs. And then you’ve got that food in front of you coming in through your eyes and your nose and sending signals your unconscious brain. I would love a Federal junk food tax. If there’s any single thing which would help, that would be a good place to start, along with making restaurants responsible for providing reasonably sized portions. Subsidizing weight loss programs. And I think it’s important to continue ongoing efforts to eliminate false claims and promises that don’t work. Because if you take the pressure off that, it will be even worse. But this is where the action is really needed.

Consumers are not at fault

I think there’s a great resistance to taking the responsibility away from the consumer. Consumers feel guilty. They feel it’s their problem. The government tells them to count calories and exercise more and things like that, but consumers can’t do this because they are just eating to feel normal. In this environment they’re just eating to feel normal, and the environment needs to changed for the relationship between what’s normal in calorie intake to be balanced out.

There’s a lot of money and health to be saved here. And it would be very fixable if the government was willing to get involved. So I think that the more you guys are willing to put this on the table as an important issue, the better everybody would be. I’m a weight loss scientist. I have a diet book out there, trying to help individuals. But it’s an uphill struggle for everybody to lose weight in this environment. And it would be much better if we accepted that this is not just the consumer’s responsibility to deal with. And to help them starting and responding actually.

So thank you very much.

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