Eric Ravussin, Ph.D.

which is basically we eat according to our resting metabolic rate, because fat-free mass is the major determinant of your resting metabolic rate. But what are the signals? I don't know. I still don't know. We have to be modest here and say there are still things that we don't understand when it comes to this energy balance.

which is basically we eat according to our resting metabolic rate, because fat-free mass is the major determinant of your resting metabolic rate. But what are the signals? I don't know. I still don't know. We have to be modest here and say there are still things that we don't understand when it comes to this energy balance.

Now I can understand that why you don't gain five kilograms over this coming year. Because in response to creeping up your weight, you burn more energy. If you do the same physical activity, this extra 5 kilos or 10 pounds is going to cost you more energy. Your resting metabolic rate is creeping up and basically you offset that. But why are we so good at maintaining, like you said,

Now I can understand that why you don't gain five kilograms over this coming year. Because in response to creeping up your weight, you burn more energy. If you do the same physical activity, this extra 5 kilos or 10 pounds is going to cost you more energy. Your resting metabolic rate is creeping up and basically you offset that. But why are we so good at maintaining, like you said,

within a couple of pounds over a year or two years or three years or five years. And I think that we are still missing some signals, but I think that there are signals coming from when FGF21, which is a signal coming from the liver, was discovered. I said, oh, maybe that is. Or when you have some of the myokines coming from the skeletal muscle, I said, maybe this is it. And it's not been it.

within a couple of pounds over a year or two years or three years or five years. And I think that we are still missing some signals, but I think that there are signals coming from when FGF21, which is a signal coming from the liver, was discovered. I said, oh, maybe that is. Or when you have some of the myokines coming from the skeletal muscle, I said, maybe this is it. And it's not been it.

And I think that we have to be modest and say, hey, we still have things to discover when it comes to this regulation of energy balance. But as a population, we have not been very good. I mean, from the 1980s to 2010, the American population has gained 10 kilograms. It's 22 pounds in 30 years. It means that there is still the major driver is this environment.

And I think that we have to be modest and say, hey, we still have things to discover when it comes to this regulation of energy balance. But as a population, we have not been very good. I mean, from the 1980s to 2010, the American population has gained 10 kilograms. It's 22 pounds in 30 years. It means that there is still the major driver is this environment.

And the change in the environment has been the trigger of this weight gain. But of course, some people are successful, some are less, and this is a problem. And of course, now we have an epidemic of obesity. It has replaced the contagious disease of the past, and now we have all these constellations of conditions which are associated with obesity.

And the change in the environment has been the trigger of this weight gain. But of course, some people are successful, some are less, and this is a problem. And of course, now we have an epidemic of obesity. It has replaced the contagious disease of the past, and now we have all these constellations of conditions which are associated with obesity.

Yeah. Peter, when I first joined the NIH, I did a study in Pima Indians, who are very prone to weight gain, as you know. And we measure in 150 people the 24-hour energy expenditure, as well as the resting metabolic rate. And we found that there was large variability in between people after adjusting for their body size, fat free mass and fat mass.

Yeah. Peter, when I first joined the NIH, I did a study in Pima Indians, who are very prone to weight gain, as you know. And we measure in 150 people the 24-hour energy expenditure, as well as the resting metabolic rate. And we found that there was large variability in between people after adjusting for their body size, fat free mass and fat mass.

Now we do better because we have organ size and we do MRI and all these kind of things. But there is variability and this variability is associated with family membership. In other words, we can say that there is a genetic background to that. But what we found was that those people in the lower tertile of this metabolic rate adjusted for body size were at much higher risk of gaining weight.

Now we do better because we have organ size and we do MRI and all these kind of things. But there is variability and this variability is associated with family membership. In other words, we can say that there is a genetic background to that. But what we found was that those people in the lower tertile of this metabolic rate adjusted for body size were at much higher risk of gaining weight.

But when we tried to attribute the weight gain either to energy expenditure being low or the other side of the equation, intake was 80%. It reminds me, there are so many systems which are basically regulating energy expenditure and food intake. Take nicotine. Nicotine is a stimulant of energy expenditure. Smokers have higher metabolic rate. but they have less appetite.

But when we tried to attribute the weight gain either to energy expenditure being low or the other side of the equation, intake was 80%. It reminds me, there are so many systems which are basically regulating energy expenditure and food intake. Take nicotine. Nicotine is a stimulant of energy expenditure. Smokers have higher metabolic rate. but they have less appetite.

Take the activity of your sympathetic nervous system. It is also thermogenic, but it cut appetite. And I think that we have to understand better these two systems. But to answer your question, I would say 80% is on the side of the energy intake.

Take the activity of your sympathetic nervous system. It is also thermogenic, but it cut appetite. And I think that we have to understand better these two systems. But to answer your question, I would say 80% is on the side of the energy intake.

And, you know, for example, sorry to interrupt, but we know that exercise is pretty bad for weight loss. If you just tell people, okay, go to the gym three times, or you even do under supervision, people don't lose weight. And Donnelly at University of Kansas has done a ton of study like that. And the physical activity for weight loss is a B minus at best in terms of evidence that it plays a role.

And, you know, for example, sorry to interrupt, but we know that exercise is pretty bad for weight loss. If you just tell people, okay, go to the gym three times, or you even do under supervision, people don't lose weight. And Donnelly at University of Kansas has done a ton of study like that. And the physical activity for weight loss is a B minus at best in terms of evidence that it plays a role.