I Can Make You Fat…Insulin – Hormonal Obesity III

By Jason Fung, MD

Click here for Hormonal Obesity Part I, and Part II

In the current epidemic of obesity, there is a clear turning point in 1977.  What was the reason?

Perhaps the increased use of cars is the underlying cause of obesity.  The increasingly sedentary lives and lack of exercise then led to obesity.  We will address the myth of exercise in an upcoming series.

On closer examination, this ‘Cars’ hypothesis holds water like a straw basket.  Look at this recent report by the US Public Interest Group on driving behaviour.
The number of vehicle miles and the per capita numbers increase continuously from 1946 to 2007.  There is no sharp upward spike starting in 1977.

If the increase in cars is the major factor driving obesity – how does that explain the sudden turn in 1977?  It doesn’t.  This theory is as incomplete as a circus without clowns.  Scary….

It is a similar story for those who would consider that the increase in fast food restaurants is responsible for obesity.  While I do not deny that fast food, which is highly processed and full of fattening carbohydrates, is fattening, there is no sharp upward spike in the number of restaurants in 1977.  There is just a gradual increase over the decades.

The increasing use of cars and fast food may contribute to the underlying slow rise in obesity rate but what caused the sudden increase in 1977?  My best guess is the odious Dietary Guidelines for Americans 1977.  In a move as absurd as hiring a street vendor to run a major corporation, we suddenly shifted from Mom-based dietary advice to US government sanctioned dietary advice.

This advice was not decided by scientific consensus.  There was no medical consensus.  It was instead decided over several days by a politician.  And what was that advice?  Eat more carbohydrates.  Eat less fat and saturated fat.  Result?  The obesity epidemic.  What else did we expect when you take dietary advice from a politician?
So what causes obesity?  What is the aetiology?  According to traditional views like Charles Banting – it was the sugars and the starchy foods that cause obesity.  Before the caloric view became popular, there was another school of thought – predominantly German and European thinkers.  World War II essentially wiped out most of the European thinkers and the flawed caloric interpretation became nutritional orthodoxy.

Obesity was hypothesized to be a hormonal dysregulation of fat mass.  That is, there is a hormonal signal from the body that controls fat mass.  For example, thyroid stimulating hormone (TSH) controls the thyroid.  Growth hormone (GH) controls growth of cells.  Sex hormones (testosterone and estrogen) control sexual maturation.  These are called endocrine glands and the substances that control them are hormones.  This is the hormonal Obesity Theory (HOT).

Fat mass should also be under hormonal control.  The major stimulus to gain fat cells (obesity) is likely insulin.  To a lesser extent, cortisol plays a role.  Hormones are the signal for the body to become obese.  Therefore, under this signal, we undertake behaviors to become obese – that is we eat more or exercise less or decrease total energy expenditure.

There are several advantages to this theory.  First, the fat cells, like all other systems in the body are under hormonal control.  That is, it is not simply up to our conscious brain to decide whether to eat or not, but under automatic control.  This takes into account both hunger and basal metabolic rate.

Also, this means that calories in and calories out are inextricably linked to each other.  They will work together to either increase or decrease obesity based on the hormonal signals.  As we have seen in the previous Calories series, caloric intake and expenditure are tightly syncronized.

If this theory is true, then this should be an extremely easy hypothesis to prove or disprove.  If insulin causes obesity (its aetiology), then we can simply give more insulin and watch to see if people become obese.

Insulin was discovered in 1921 by Banting and Best at the University of Toronto.  Type I diabetes is a disease that results from the autoimmune destruction of the insulin producing cells in the pancreas.  This results in extremely low levels of insulin and insulin injections led to the miraculous cure of this disease.  But it also had other uses.  By 1923, it was being used as a fattening agent for chronically underweight children.

So here’s the million dollar question.  If insulin causes obesity, then giving insulin should cause weight gain.  If I give somebody insulin, will it make them fat?  The short answer is YES.

In fact, almost any physician who prescribes insulin to patients with type I or type II diabetes already knows this to be a fact.  Patients taking insulin are also more than well aware of this.

Insulin causes obesity!  The more insulin you give, the more obesity you get.  This is simply an undeniable fact of life.

Let’s look at an early study in type I diabetics.

Influence of intensive diabetes treatment on body weight and composition of adults with type 1 diabetes in the Diabetes Control and Complications Trial

Type I diabetics require insulin in order to survive.  In this trial, they randomized 2 groups of patients.  One group would get a minimal amount of insulin.  The other group would get larger doses to keep the sugars under tight control.

The idea, which was proven, was that tight control of sugars helped to reduce complications of diabetes.  However, what happened to weight gain?  You can see from the graph above that the group with larger doses of insulin (open bars) over a 9 year period developed significantly more problems with major weight gain than did the group with lower doses (shaded).

Yowzers!  By 9 years of follow up, over 30% of patients had “major” weight gain!  Hefty hefty.  Were these patients lacking in willpower?  Were they lazier than before?  Were they more gluttonous?  No No and No.  They got insulin.  It made them fat.

In fact, there is a direct correlation between both the total insulin dose and the mean serum insulin and weight gain.  There is a dose-response relationship.
The higher the dose of insulin, the more weight gained.  The higher the blood levels of insulin, the more weight gained.

What about type 2 diabetics?  Sometimes these patients also take insulin.  A study to address this exact issue was entitled

Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treament and risk of complications in patients with type 2 diabetes” Lancet 1998 Sep 12;352(9131):837-53

In type 2 diabetes increased insulin dosage causes obesity.  At the beginning of the study, the weight is the same in both groups.  They are randomized to treatment containing more or less insulin.  Those with higher doses of insulin gained more weight.

All this leads to the inescapable conclusion from this study that Insulin causes Obesity.  Those who took more insulin gained an extra 10.5 pounds on average compared to those that took less insulin.

In other words – I can make you fat.  I can make anybody fat.  I just need to give enough insulin.

Continue to Insulin Causes Weight Gain – Hormonal Obesity IV here
Begin here with Calories I
Click here to see the entire lecture: The Aetiology of Obesity 1/6 – A New Hope

By The Fasting Method

For many health reasons, losing weight is important. It can improve your blood sugars, blood pressure and metabolic health, lowering your risk of heart disease, stroke and cancer. But it’s not easy. That’s where we can help.

Jason Fung, MD

By Jason Fung, MD

Jason Fung, M.D., is a Toronto-based nephrologist (kidney specialist) and a world leading expert in intermittent fasting and low-carb diets.

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