Why are There Fat Doctors?

The energy balance model of weight management is wrong

Many people adhere, explicitly or implicitly, to the Energy Balance Model of weight management. If you are overweight, and go to visit your doctor, s/he will likely tell you to try to lose some weight — and your doctor will likely advise you to “eat less and move more.” This advice is based on the EBM of weight management, whether your doctor knows it or not.

It sounds logical and fits with the belief that overweight people became overweight by eating too much and/or not moving around enough — they are gluttons and/or sloths.

But for this to hold true — that overweight people are gluttons and/or sloths — it would mean that gluttony and sloth took a sharp increase in societies around the world over the past 60 years. For this to be true, it would mean that for some reason, people gave up on willpower. Even doctors! As a former fat person myself, if losing weight is as easy as eating less and/or moving more, there wouldn’t be any fat people.

Prominent British cardiologist, Dr. Aseem Malhotra, in a pre-Brexit presentation to the EU, pointed out that 50% of NHS workers are overweight. Closer to home, Dr. Katherine Barnett references a recent Physicians Health Study that found 40% of the 19,000 doctors surveyed were overweight and 23% were obese. So have all these health care workers simply lost their willpower and fail to take their own advice?

That’s one possibility. Another possibility is that the advice doctors have been giving for decades — and the model the advice is based on — are wrong.

As mentioned above, the standard advice of “eat less/move more” is based on the EBM of weight management. The advice centers on the assumption that people gain weight by eating too much and/or exercising too little. The idea, then, is to reverse this process by eating less and/or moving more. Said a different way, the assumption is that people gain weight by putting too much energy into the system (they eat too much) and/or by not expending enough energy (they don’t exercise enough). So, to reverse weight gain, overweight people need to put less energy into the system (eat less) and/or expend more energy (move more).

A fundamental assumption of this Energy Balance Model is that the energy you put into the system is independent of the energy that gets expended. So, all you need to do is operate in an energy deficit to lose weight. This energy deficit — relative to your current energy input/output — can, according to the model, be achieved by eating less and/or moving more. Simple. Yet completely ineffective for long-term weight loss.

Why? Because the fundamental assumption that “energy in” is independent of “energy out” is not true. When you operate at an energy deficit, you will initially lose weight. But soon after, weight loss stalls and weight gain occurs — even though you are eating less than before and/or exercising more. This is because weight management is a homeostatic process: energy in and energy out are dependent. When you operate at an energy deficit, your body adjusts its output to counteract that deficit. This has been known for over a century.

Enter the Hormonal Model of Weight Management.

The Hormonal Model (HM) is based on our knowledge of several key hormones related to metabolism in general and weight management in particular. While many hormones are involved in weight management, there are three key players: Insulin, glucagon and leptin.

Insulin plays several roles within the body, chief of which is to maintain levels of blood glucose within a safe range. We need a base level of glucose in our blood at all times. When it gets too high (like after a meal including carbohydrate), insulin takes glucose to any cell that can use it (which is most of our cells). What can’t be used by our cells gets taken to the liver and converted to glycogen (a denser form of glucose). Glycogen is then transported (again by insulin) to muscle cells, which can store glycogen for use later. If the muscle cells are full and there is still glycogen and/or glucose in the blood, insulin takes it back to the liver for storage (although the liver has a limited capacity to store glycogen) or to be converted to fat. Any fat that the liver can’t hold is transported (again by insulin) to our fat cells for storage for later use. Our fat cells aren’t very limited in how much fat they can hold. But when they get to a certain threshold size, they secrete a hormone called leptin, which tells us we are full and to stop eating.

When we are between meals, and the process is running to spec, insulin levels fall and allow the hormone called glucagon to promote the use of body fat for energy.

If your weight management system is running to spec, you will likely maintain a consistent weight over time. In fact, if you eat more than usual on a given day (more energy in than usual) your body will do a couple of things to maintain a consistent weight: it will speed up your metabolism (you might feel warmer than usual, be more fidgety than usual, have a desire to go for a walk or ride your bike) and/or reduce hunger signals — you will simply not be so hungry later: you might skip a meal or eat far less than usual. All this is done to expend the extra energy you took in and maintain your weight.

The reaction described above illustrates the dependency between energy in and energy out. And the dependency works with a deficit, as well. If you eat, say, 1500 calories a day instead of a usual 2000, your body will either send you hunger signals to get you to eat and to eat more than usual, or it will slow down your metabolism to counteract the deficit — you might feel sluggish during the day, find you are watching more TV, etc. Even if you work out to the tune of 500 calories a day (instead of eating less) your body will try to get you to eat more or do less the rest of the day.

So if the Hormonal Model of weight management is true, why do people — including doctors — get fat? Here’s why:

Eating carbohydrate causes a spike in insulin — your body does this to guard against having too much glucose (which is what you get when carbohydrate is broken down in your digestive system) in your blood. Too much glucose can lead to a lot of problems — so your body has a safety system to lower blood glucose levels. For many people, eating a diet high in carbohydrate (as the one promoted by the Food Pyramid) causes their cells to become resistant to insulin signaling — the net result being that they need the body to generate and secrete more and more insulin to do the job described above as time goes by.

This increased insulin secretion causes a cascade of negative reactions. Higher levels of insulin in the blood to address glucose levels means it takes longer for the level of insulin in the blood to get low enough for glucagon to promote using body fat for energy. A sign of this is needing a snack between meals. If you need a snack between meals, it means you aren’t using body fat for energy. People whose weight management system is running to spec don’t get hungry between meals because they are, in effect, eating their body fat between meals.

If you aren’t using body fat for energy you just keep accumulating it. Your fat cells are supposed to signal the brain to stop eating when they get full — via the hormone leptin. But when insulin levels in the blood are high, it impairs leptin signaling. This makes sense given you have only a few hours of easily-accessed, glucose-based energy in your body at any given time. So if body fat isn’t available for energy, you have to be ready to eat every few hours.

Many doctors have recently started advising their patients to eat 5 or 6 times a day. This is a reaction to the symptom of always being hungry. But many doctors aren’t taught nutrition, so they don’t realize that treating this symptom is only making the problem worse. They just assume, when their patients come back a year later heavier than before, that they are just lacking willpower. They can’t imagine that their advice is wrong. But it is.

Many nutritionists are told that glucose (and so, carbohydrate) is the main fuel source for the human body. This is true if you eat a lot of carbohydrate. What they aren’t taught is that a diet high in carbohydrate can prevent the body from utilizing a much bigger “battery” than stored glucose — stored body fat. The ironic thing is that they support a high carbohydrate diet because in their mind, glucose is the only fuel the body has available. And this is simply not true. In fact, carbohydrate is a non-essential nutrient for humans. Yes — we need glucose. But if we don’t eat any carbohydrate, our liver produces all the glucose our body needs. And you know what it converts into this needed glucose? Body fat. It’s almost like we evolved to eat a low-carbohydrate diet that would allow is to store a little bit of fat at every meal, and then use that fat for energy between meals…

What can one do to lose weight? In general, one needs to work with (not against) how the body manages weight. Eat less/Move more works against the homeostatic weight management system your body has. When you fight your body, it fights back — and usually wins. I used the information, discussed in detail in my book, to lose 175 pounds. It shows how your body works — and when you understand how it reacts to the food you eat, how to work with your body to lower your weight becomes extremely obvious.

I wrote a book about nutrition, metabolism and weight management based on the information I used to lose nearly 50% of my body weight. It’s all based on science and it’s available on Amazon. See my profile page for more details, if you are interested.

References:

Barnett, KG, Global Advances in Health Medicine, v.3(6); 2014 Nov

Berg, JM et al. Biochemistry (9th edition), 2019.