23 Aug 2016 ‘We don’t say fat mice have poor willpower’: rethinking obesity
It seems that the only thing we truly know about the standard obesity treatment is that it fails.” Here’s an enlightening conversation between two leading US obesity experts, Dr David Ludwig and Dr David Perlmutter.
Dr David Ludwig (left) has a multitude of titles: MD, PhD, endocrinologist, researcher, professor, and author.
His bestseller, Always Hungry? explores the effects of diet on hormones, metabolism, and body weight.
He sat down with fellow author and physician, Dr David Perlmutter, to discuss dietary approaches to treating chronic illness, the hopelessness of counting calories, and why full-fat yoghurt shouldn’t be a guilty pleasure.
Perlmutter: If this is a book about appetite — making the right dietary choices in order to regain a healthy weight — how does an endocrinologist like yourself fit in?
Ludwig: Even though diet and lifestyle cause most cases of heart disease, diabetes, and even cancer, medical school is notorious for having very little nutrition. We focus almost exclusively on drugs. But humans didn’t evolve to respond to drugs. We evolved to respond to hormones, those powerful signals that tell the rest of the body how to act in a coordinated fashion.
During my medical training, I realised the implications of endocrinology to nutrition without ever having been inculcated in the standard nutritional paradigm of calories in, calories out.
The standard teaching is that diet is a delivery system for calories and nutrients, but it’s so much more. Every time we eat, our hormones, metabolism and the expression of our genes change in ways that have to do with whether we’re going to be hungry or satisfied after a meal. Whether we’re going to gain weight, struggle with cravings, or have a healthy body weight.
Bringing endocrinology to understanding food opens up a vast new field of interest in research and also in the clinic with my patients.
Perlmutter: There are a lot of books written about this or that weight loss program, but you’re actually in the trenches applying your ideas with patients daily. It’s empowering that we can manipulate our food choices, which has such a broad range of physiological effects.
Ludwig: I started my career the way that many people have treated obesity weight issues, which is a focus on calorie balance. I told my patients to eat less and exercise more. They’d come back in a few months almost inevitably gaining weight.
Around the mid-nineties, I started thinking about food from this endocrinological perspective. It completely altered my approach.
As I’ve mentioned before, the calorie-focused model might work if you’re a toaster oven, but humans aren’t machines. When we cut back on calories, the body responds. People don’t just get hungry, their metabolism crashes, and they inevitably gain weight.
Unfortunately, we’ve been using the same approach to obesity that was initially formulated when blood letting was a dominant treatment for all sorts of chronic diseases. It seems that the only thing we truly know about the standard obesity treatment is that it fails. That’s really the most notable finding.
Despite a century of elaborate behavioural methods and psychological approaches to help people do something as simple as eat less and move more almost nobody can do it! Maybe for a few months, but two years down the road, many people end up even heavier than they previously were.
We need a new paradigm. Always Hungry? explores the notion that overeating doesn’t make you fat; the process of getting fat makes you overeat.
Perlmutter: One of my favourite points in your book is the idea that all fats are not created equal. That the type of fat we ingest matters significantly. Decreasing simple sugars and carbohydrates while increasing fat isn’t exactly a new concept. And yet, there is still criticism.
Ludwig: Yes, absolutely. My research group has been investigating this for twenty years, but it’s built on a century of research that goes back way before Atkins.
Body weight is regulated by our biology more than our willpower. We’ve known that for a while now. In fact, I started my career in the laboratory, making transgenic mice, doing these kinds of studies. If you feed a mouse a certain kind of food, or change its hormones in a certain way, it gets fat. We don’t say the mouse has poor willpower.
This knowledge, sadly, hasn’t made the leap into clinical care. People feel like it’s their fault that they’re fat. That’s a terrible burden, especially in our society. We do not tolerate discrimination in many ways, but around obesity – just turn on the TV and you’ll hear jokes.
We have to look at obesity like any other chronic disease in order to generate more effective treatments and relieve people of this huge stigma and burden that they’ve been carrying.
Perlmutter: I’d go all the way back to the fossil record. Back 1.8 million years ago. It’s pretty clear that there wasn’t real accessibility to either simple carbohydrates or an abundance of complex carbohydrates. This signalling of caloric scarcity plays a huge role in why people gain and can’t get rid of unwanted weight. Let’s explore that a little bit — what locks fat up and makes it unavailable to be used as fuel?
Ludwig: We can think about our metabolism as like a tide. We’re not like protozoa that continuously absorb nutrients from our environment. We eat episodically, and when we have food. This was true when we were hunter gatherers and today.
When we sit down and eat a meal, we temporarily have a calorie surplus. The calories flow into the body and insulin increases to direct them into their storage sites: fat, muscle and liver. That’s how it should be because a few hours later, we won’t be eating.
When insulin levels decrease, that’s the metabolic signal for calories to flow back out and become available to the brain or the rest of the body. When we eat highly processed carbohydrates — white bread, white rice, all those foods that flooded our diet during the low fat years — that makes insulin rise even higher than it would normally and this other hormone, glucagon, suppress. Glucagon is the yang to insulin’s yin or vice versa.
Insulin is anabolic and promotes storage. Glucagon is catabolic and pulls out calories. If you have too much storage and too little counter-influence, you have this overwhelmingly strong signal to the body to store calories.
A few hours after you finish the meal, those calories are still trapped when they should be flowing back out. The brain, which is critically dependent on a steady supply of calories, sees calories in the blood declining and begins to panic. The first thing it does is make you hungry.
If you do what low-calorie diets tell you to do, ignore your hunger, calories keep going down and then we have a metabolic emergency. The brain now panics and you can’t think about anything besides food. Stress hormones are secreted that try to pull calories out of storage fat like with a wrench.
You won’t die but these cycles lead to weight gain and increased chronic disease risk. We need to eat in ways that allow the flow of calories to be more gentle. Then we can more easily access the calories three, four hours after a meal…..