Wednesday, 8 January 2014


It's resolution time.  A time when many people try to lose weight and get healthy.  Most don't succeed.  They may do well for a month or two, or maybe six, but the vast majority give up and eventually put back on all the weight they may have lost.  Most people believe they fail because they aren't disciplined enough, they are weak and have no will power.  Maybe there is another more obvious reason why these calorie restricted diet plans fail so often.

Maybe they are Hungry!!

Now I'm not talking about hunger that comes from boredom or seeing a pizza commercial.  I'm talking about physiological hunger that comes from metabolic disturbances that leads to unbalanced hormones.  There actually is quite a bit of good science on hunger.  J. Stanton wrote a great series on hunger on his blog at (1).  He also gave a talk on hunger at the Ancestral Health Symposium that you can watch on youtube.  (2).  I will try to summarize a few points from his blog post here.

Why are we hungry?  What is metabolic flexibility?

We assume that people gain weight because they eat too much.  But what if we have the causal relationship mixed up. There is evidence that for at least some people, they eat too much because they are gaining weight. This fact is obvious when we talk about vertical growth.  No one would say that the biggest difference between someone who is 7' tall and someone who is 5'6" is that the tall person ate more and moved less! Do you really believe that they would only be 6' tall if they ate less?  Although it is true that a 7' tall 300 lb person would have to eat more than a 5'6" tall 140 lb person, they don't get taller because they eat more.  They get taller because they are secreting more hormones that promote growth.  As a result they have an increased appetite and they eat more and grow taller.  So if people eat more because hormones are making them grow taller why don't we ever ask if other people eat more because a hormonal imbalance is making them grow wider?

One factor that can contribute to this hormonal imbalance is a loss of metabolic flexibility.  We have two main sources of energy for our bodies, fat and glucose.  Studies have shown that obese people have a broken metabolism and don't burn fat very well (3).

Here are a couple of interesting points from the cited study:
  • Normal subjects are burning 30% more calories at rest than the formerly obese.
  • Normal subjects are burning 7% carbs and 78% fat at rest, whereas formerly obese subjects are burning 49% carbs and 34% fat at rest
 Our bodies can only store a small amount of glucose, but even a lean person will have at least 50 000 calories of stored body fat.  People who burn higher amounts of glucose will use their stored glucose much faster than a metabolically flexible person who is burning mostly fat.  A few hours after eating, their brains realize they are using up their stored glucose and it starts conserving glucose by lowering blood sugar.  Your brain takes priority because if your brain doesn't have energy you die.  Low blood sugar causes fatigue, brain fog, and a hormonal response that leads to insatiable hunger.  Meanwhile, the metabolically flexible skinny person has been burning mostly fat so they have plenty of stored glucose left.  Their brain is happy and their blood sugar is more stable.  They don't get the hormonal response that increases hunger.  For them it doesn't take much willpower to walk by the vending machine at 11 a.m. since they are not hungry.  For the metabolically damaged obese person who has low blood sugar and large amounts of circulating hunger hormones it takes a HUGE amount of willpower to walk by the vending machine without getting a snack.

 Why are we hungry?  Malnutrition?


Another factor that can affect hunger is malnutrition.  We live in a food culture today that provides us with more calories than we need, but does not provide us with the nutrients we need.  Research has shown that nutrient deficiencies can lead to over consumption.

In this study (4) two groups of rats were fed the same diet, but one group was supplemented with 25 vitamins and minerals.  They were then given unlimited access to a sugar water solution as well as their regular food.  .
  • The supplemented rats ate 60% less sugar than the rats who weren't supplemented.
So the researchers didn't have to tax sugar, or make the rats feel guilty about being a glutton, all they had to do to reduce sugar consumption was to increase the nutrient density of their diets!!

These two studies looked into the effect of  multivitamins (5).  In one study, both the supplemented and non supplemented groups ate as much as they wanted.  In the other study, both groups were on calorie controlled diets and consumed the same amount of calories.

  • In the first study the supplemented group had a lower body weight, lower fat mass and a tendency for greater resting energy expenditure.
  • In the second study the weight loss was the same in both groups but the supplemented group reported less hunger.

So what does this all mean?


A few take away points that may help you if your New Years Resolution is to lose weight. 

Most of the time people who try to lose weight by eating less and moving more fail (6) .  The biggest reason for this is that eating less and moving more makes you hungry.  You can fight your hunger for a while, but eventually your physiology will win. 

If you have a broken metabolism, then eating less of the same diet that contributed to your broken metabolism will not fix the problem.

Even worse, if you are malnourished, eating less of the same diet will make you even more malnourished!

To increase your chances of being successful you have to change what you eat, not just how much you eat. 

A high fat, low carb diet out performs a low fat diet in virtually every study comparing a low fat calorie restricted diet to a high fat, low carb diet (7).  High fat diets lead to greater weight loss as well as greater improvements in heart disease risk factors!!

A high fat, low carb paleo diet forces your body to become metabolically flexible again.  By restricting your bodies access to glucose you force it to up regulate the metabolic pathways and enzymes needed to burn fat.  You may feel lethargic for a couple weeks during this process, but once you become metabolically flexible and start relying on fat as a fuel instead of glucose you will have increased energy and much lower hunger.

A high fat paleo diet also includes some of the most nutrient dense foods on the planet.  Meat, especially organ meat like liver, eggs, fatty fish and non starchy vegetables are packed with nutrients.  More nutrients will mean less hunger.   After being low carb for a few months you can start adding in some sweet potato, white potato or white rice and see how you react.  Everyone has a different carb tolerence based on activity levels, genetics and metabolic health.