Monday, August 1, 2011

Why We Get Fat

You've heard this advice before:
  • Take in less calories than you expend, and you can lose weight
  • Avoid fat; it makes you fat!
  • Aim for 6-11 servings of whole grains every day
  • Eat as many fruits and vegetables as you'd like per day
  • If you're overweight?  Eat less and exercise more
  • Consumption of fats causes heart disease and clogs arteries
  • Increased fat intake causes high cholesterol
  • South Beach, Atkins, Ornish, Mediterranean Diets; They're all the same!
  • Genetics are what determines if you are skinny or fat.  It's your parents' fault. 

In his book, Why We Get Fat, author Gary Taubes addresses these common myths and, with scientific evidence and proven research behind him, literally destroys what the 'experts' have been saying.  In his sources, there are over 16 pages of research articles, books, and evidence of how the above statements are NOT true.

While reading this book, his physiological explanations are something any personal trainer or strength coach should consider adopting, as they appeal to the general population.  In addition, there are many strength coaches, personal trainers and nutritionists who give out the advice above, and quite frankly, are wrong.

Taubes' review of research has really pointed a finger at a few chief causes of obesity and weight gain, but let's start with one of chief causes: 


Imagine just thinking about food.  No, really.  Think about food.

Insulin was just released from your pancreas to help digest the incoming food.  Most people, when they think about food, eat shortly thereafter.  The body's way of preparing for the incoming nutrients?  Being ready when the meal enters the esophagus and passes into the digestive tract.

So what does insulin actually do?  It's primary role, to keep blood sugar under control, happens once food is thought of, and is then consistently secreted down to the last bite.  Then, the insulin signals other cells throughout the body to increase the rate at which they pump glucose from the bloodstream.   

This is where the magic either happens or it doesn't:  the cells will either burn some glucose for immediate energy, store some for later use, muscle cells will store glucose in the form of 'glycogen', and then some liver cells store some as glycogen but also convert to fat.  Worst case scenario?  Fat cells store it as fat.  

Thus, insulin is secreted primarily in response to the carbohydrates in your diet in order to keep blood sugar under control.

Then what's the big deal with insulin, and why is it a cause of obesity? 
Insulin works to store both fat and protein, making sure your muscle cells get enough fuel to repair and rebuild after workouts, and also stores enough fuel (glycogen and fat and protein) to function between meals.  Taking in carbohydrates causes blood sugar and insulin levels to rise, and our most efficient fuel stores (muscles and liver which store glycogen) only have so much 'room at the Inn'.  Once our essential fuel stores are full, our fat cells are next for storage, and this is where the fat storing damage comes in.

In summary, one of Taubes best summaries of how fat storage happens, (contrary to popular wisdom): 
  1. Think about eating a meal containing carbohydrates
  2. Start secreting insulin
  3. Insulin signals fat cells to shut down the release of fatty acids and take up more fatty acids from circulation
  4. Start to get hungry, or hungrier
  5. Begin eating
  6. Secrete more insulin
  7. Carbs are digested and enter circulation as glucose, causing blood sugar levels to rise
  8. Secrete more insulin
  9. Fat from diet is stored as triglycerides in the fat cells, as are some of the carbs that are converted into fat in the liver
  10. Fat cells get fatter/bigger
  11. So do you
  12. Fat stays in fat cells until the insulin level drops
So what's the key to losing fat?  Managing insulin!  In the chart below, you'll see a consistent level of blood sugar.  Basically, while blood sugar remains in the middle as a result of eating fewer or no carbohydrates, you will be able to burn fat from the fat cells as energy (insulin will not need to be released at the high rates carbohydrates demand). 

The next question most have, is what to eat throughout the day instead of carbohydrates.  Try the following, as recommended by the Lifestyle Medicine Clinic at Duke University Medical Center:

whole eggs and egg whites (combination is best)
salad greens, including spinach and other leafy veggies
Cheese (up to 4 ounces a day)
Cream (up to 4 tablespoons a day)
Snacks: Nuts, pepperoni slices

Each meal should contain greens, fat, and protein.

If it sounds like Atkins, you're right.  Small differences, and the explanations why dietary fat does NOT cause heart disease and cholesterol related issues, coming by the end of this week.

Source: Taubes, Gary, 2011.  Why We Get Fat.  New York: Alfred Knopf.   

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