How Caloric Reduction Wrecks your Metabolism – Calories Part VI

Click here for Calories part I, part II, part III, part IV, and part V. In previous posts, we have reviewed how eating less does not result in permanent weight loss. In the classic studies of caloric reduction the result was a significantly lowered metabolic rate or Total Energy Expenditure (TEE).

Let’s now fast forward to the modern era, and look at this study published in the prestigious New England Journal of Medicine.

Changes-in-Energy-Expenditure-1Changes in Energy Expenditure Resulting from Altered Body Weight
Rudolph L. Leibel NEJM 1995 march 9, 332 (10); 621-28

In this experiment, 18 obese and 23 non obese subjects with a stable weight were recruited. They were fed a liquid diet of 45% carbohydrate, 40% fat and 15% protein until the desired weight loss or weight gain was achieved.

One group targeted a 10% weight loss and the other group targeted a 10% weight gain. After weight gain, subjects were then returned to their initial weight, and then a further 10% or 20% weight loss was achieved.

The question they wanted to answer was what happened to TEE when weight was increased or decreased. This was achieved without a change in the composition of the diet. That is, the liquid diet was a constant ratio of carbohydrates, fats and protein. The only variable was the total intake of this liquid diet. What happens to TEE when caloric intake is varied?

In other words, if we reduce or increase our Calories In, what happens to Calories Out? According to the conventional Caloric Reduction as Primary (CRaP) hypothesis, as Calories In go up or down, there should be not much change in the Calories Out. Great! This is exactly what we want to know as well, because we don’t really like the answers the classic studies gave.

Changes-in-Energy-Expenditure-2-300x225
Results

Well, what happened? The results graph to the left shows the changes in TEE with the different experimental groups. Let’s start by looking at the 10% weight gain group. In response to the weight gain people increased their energy expenditure by almost 500 calories/day.

Remember that one of the key assumptions of the CRaP theory is that in response to caloric change, TEE does not change. This is clearly NOT TRUE.

Instead of a simple calories in, calories out model where fat is deposited according to an excessive intake of calories, it appears that the body responds to excess calories by trying to burn it off!

Now let’s see what happens as the weight is returned to normal. Here things start to get really interesting. As weight returns to normal, TEE returns to baseline. As we move into 10% and 20% weight loss, the body reduces TEE by about 300 or 400 calories per day.

So, as we begin to lose weight, the body responds to the weight loss by reducing TEE, thereby slowing down further weight loss, and encouraging weight regain. This is all done without changing the dietary composition of the food, since all participants were taking in the same liquid diet. In other words, an increase in Calories In causes an increase in Calories Out. A decrease of Calories In causes a decrease in Calories Out. This, of course, tends to minimize the effect of the increase or decrease of caloric intake.

If you were trying to lose weight by eating less (Caloric Reduction as Primary), this is where you go “WTF?!! OMG, That sucks!”

Thermostat
Thermostat

Rather than the simple balancing scale of calories in calories out, it appears that our body acts much more like a thermostat. That is, the body seems to have a certain Body Set Weight (BSW). Any attempts to increase above this BSW will result in our body trying to return the body to its original weight by increasing TEE (increasing metabolism to burn off the excess calories).

Any attempts to decrease below this BSW will result in our body trying to return the body to its original weight by decreasing TEE (decreasing metabolism to regain lost calories). No wonder it is so hard to keep the weight off! As we slow our metabolism, we must further and further reduce our caloric intake to maintain weight loss.

Hmm. This actually makes a lot of sense. In fact, this is assumption #4 of the CRaP theory. We assume that fat gain or loss is unregulated by the body. We assume that as we eat more we keep gaining weight and as we eat less and we keep losing weight. But there is no system in the body that is unregulated like that! Everything is under hormonal control. It makes far more sense that the body has a system to control body weight. (Actually it has multiple systems).

Let’s put this into a dietary context. Suppose we are at a stable weight. We eat 2000 calories and burn 2000 calories every day. We keep our diet constant but just increase or decrease the amount. Suppose we super-size our portions but otherwise keep our diets constant.

Weight may increase but the body’s response would be to increase daily Total Energy Expenditure – body temperature may increase, energy and sense of well being may increase. We may eat 2,500 cal/day but the body has now increased TEE to 2,500 cal/day. No further weight will be gained and the body will attempt to reduce our weight back to the original. In the meantime, we feel great.

Let’s do the opposite – the misguided dietary technique of portion control. We reduce our portion size but keep meal timing and composition the same. We reduce our calorie consumption from 2000 cal/day to 1,600 cal/day. Our weight may reduce, but then the body would respond by reducing TEE to about 1,600 cal/day. We might feel cold, tired, miserable and hungry. If you have ever been on a diet – you probably know how that feels.

The worst part of it is that we don’t lose any further weight because we are eating less and burning less. Any slip in the diet, even to the previous normal 2,000 cal/day will result in weight regain. Discouragement sets in. We get tired of feeling so lousy so we go back to our regular diet. All the weight comes racing back with a little extra for good measure. In fact, this is exactly what happened in the semi starvation experiments done by Dr. Ancel Keys as well as those at the Carnegie Institution in 1917.

We feel we have failed ourselves. We think that it is our fault. Our doctors, dieticians, and other medical professionals silently criticize us for ‘failing’. Others silently think we have no ‘willpower’, and offer meaningless platitudes. Sound familiar? Yeah, I thought so.

But in truth, the failing was not ours. The portion control diet is virtually guaranteed to fail. It has been proven over and over in the last 100 years. The only reason we think that it works is because everybody – the doctors, the dieticians, the ‘scientists’, the media – has convinced us that it is all about calories.

Clearly something is causing us to gain weight, but calories sure don’t look like the problem here. What is that problem?

Continue to Calories Part VII here

Begin with Calories I

Click here to watch the entire lecture: The Aetiology of Obesity 1/6 – A New Hope

14 Responses

  1. […] We need to completely rethink our conventional view of obesity. Click here to continue to Calories part VI. […]

  2. […] of the complexity of measuring BMR, NEAT, TEF, and EPOC, we make a simple but erroneous assumption that these factors are all constant over time. This assumption leads to the crucially flawed conclusion that exercise is the only […]

  3. What are the findings of the study then? It was supposed to tell us that if we increase/decrease our weight, then our BMR increase/decrease. The results confirm that theory, but isnt the increased calorie intake the reason for increased BMR? What I am trying to say is that their BMR apparently raised, but the question is which one of these 2 factors (increased caloric intake/increased body weight) caused changes in BMR. What do you think is the answer?

    And if you say that if we increase our calorie intake by a certain number (lets say 1000 cal a day), we start gaining weight until our metabolism raise and then weight gain stops, why are there obese people which gain weight every year? According to your theory, these people are eating more and more and further increase their caloric intake every day. Because how can they otherwise keep putting on weight, if their metabolism balanced their intake? So I think that if you start eating more, your metabolism raise to some degree, but saying that the weight gain stops after some time as your BMR balance your caloric intake seems to be nonsense.

    • Christopher Chadrick Hamilton

      ” According to your theory, these people are eating more and more and further increase their caloric intake every day. Because how can they otherwise keep putting on weight, if their metabolism balanced their intake? ”

      Remember Sharal the body’s set weight is driven by insulin, not calories, eating more does indeed cause metabolism to rise, but in the presence of sugar insulin channels this energy into storage, once the consumed calories are burned off or stored the body has no need to keep metabolism high, so it returns to normal. The result is more stored fat than before… A heavier person with a slightly higher set weight driven by the excess energy stores.
      Just like, for the duration of a short term caloric reduction, the body slows down the metabolism to match intake and tries to return to the set weight once calories return.
      Once a weight is reached, the body tries to hold on to it so it can use it when food is not available.

  4. Deb Griffith

    I think it is because they become insulin resistant. I wondered the same thing…if this is true, no one would be obese. But I think the study was short term, just to measure the bmr.

    It is what kind of foods that are continually eaten. I know that several years ago, I started dating a guy who ate out every night. So of course, I started. And within months, I was the heaviest I had ever been! My bmr certainly didn’t keep up! Once I stopped eating out, I dropped 40 lbs.

  5. […] However, in the case of straight-on fasting, the caloric theory holds as promised, resulting in a weight loss very close to that predicted if Caloric Expenditure stays stable. In other words – metabolism does not decrease in fasting. A prolonged caloric reduction, on the other hand, is shown to decrease metabolism. […]

  6. John umia

    I have just come upon you site and find it very well presented. I am not a neophyte in the low carb game so almost all of what you wrote so far in this series was all very sensible and correct IMO. I would like to suggest a small change, however. The logic of calorie restricted dieting and concurrent weight loss and TEE reductions seem to be untenable because if we do lose fat, we are in fact burning fat calories which should compensate for the calorie reduction in intake. The real issue is that we are not burning as much fat as we would like, and the calorie reduction is causing hunger. The issue of hormonal control is paramount (insulin effects on HSL for expample) and has to be at least mentioned somewhere in this discourse at this stage so that we are not lead into thinking “how could be be losing weight if our TEE also drops?” in compensation for the calorie reduction. Just my 2 cents worth.

  7. […] פוסט זה מוגש כשרות לאנשים שלא יכולים ו/או קשה להם לקרוא באנגלית. הזכויות על התוכן שייכות לכותב של הפוסט המקורי. את הפוסט המקורי ניתן למצוא בכתובת הזאת. […]

  8. […] How Caloric Reduction Wrecks your Metabolism – Calories Part VI […]

  9. Connie Cason

    I am confused. If eating less calories causes your body to want to burn less calories, if we do 16:8 or 20:4 fast should we try to eat the same amount of calories as we normally would in that small time frame of eating or is eating fewer calories okay?

  10. […] So, for a patient with 100 pounds of fat to lose, you might expect that it would take roughly 200 days to lose it all. 200 days! This assumes that Caloric Expenditure remains stable with fasting, which seems to hold true. In other words – metabolism does not decrease in fasting. A prolonged caloric reduction, on the other hand, is shown to decrease metabolism. […]

  11. […] So, for a patient with 100 pounds of fat to lose, you might expect that it would take roughly 200 days to lose it all. 200 days! This assumes that Caloric Expenditure remains stable with fasting, which seems to hold true. In other words – metabolism does not decrease in fasting. A prolonged caloric reduction, on the other hand, is shown to decrease metabolism. […]

  12. […] So, for a patient with 100 pounds of fat to lose, you might expect that it would take roughly 200 days to lose it all. 200 days! This assumes that Caloric Expenditure remains stable with fasting, which seems to hold true. In other words – metabolism does not decrease in fasting. A prolonged caloric reduction, on the other hand, is shown to decrease metabolism. […]

  13. So, how do I lose weight without destroying my metabolism?

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