Why We Get Fat…

“We get fat, our physicians tell us, because we eat too much and/or move too little, and so the cure is to do the opposite.” – Michael Pollan, In Defense of Food

When my husband and I are planning a date night out to a really great restaurant and want to eat as much delicious food as possible, we often eat a light lunch or do something active to make ourselves hungrier for the big meal. But wait, that’s also what I’m told to do to lose weight…. Something’s wrong with this reasoning.

In his book, Why We Get Fat: And What to Do About It, Gary Taubes tackles this cultural mindset of “calories in, calories out,” turning it on it’s head and calling into question a principle we’ve always held to be true. It’s a fascinating read, with lots of really compelling cultural case studies and the scientific details in layman’s terms that help you to understand his argument.   I have a bad habit of reading the Appendix of a book first and will admit that I was disappointed with some of the diet recommendations he makes – in particular, okaying alternative sweeteners like Splenda and Nutrasweet and diet soda; but, I had a long plane flight ahead of me and nothing else to read so I kept on.  I’m glad I endured because there are definitely some great nuggets of information I got from this book:
 Obesity has become an epidemic.  1 in every 3 Americans are considered obese compared to only 1 in 9 fifty years ago. I’ll admit that I used to think that most people get fat by simply being lazy and/or eating too much junk food.  But, a case study of many areas of poverty shows that there are many who are malnourished (less calories in), work manual labor (more calories out), and who are still obese or overweight.  And in research studies, hormone-manipulated rats proved that they immediately began to overeat, become sedentary and quickly grew obese; even when completely deprived of food, forced to diet or forced to exercise, the rats retained their fat while their organs deteriorated.  There must be some other determining factor than being slothful and gluttonous…. it seems more to do with genes and hormones than simply overeating.  The answer lies within the fundamental definition of obesity- “a disorder of excess fat accumulation.”

Taubes relates fat tissue to a wallet: “you’re always putting fat into it and always taking fat out.”  But only certain forms of fat can go in and out, while others go in and stay. When fatty acids enter a fat cell, they join up with a glycerol molecule and two other fatty acids to become a triglyceride. Triglycerides are too big to go back out of the cell membrane, so they stay captive until they can be disassembled.  The hormone that works to create triglycerides is insulin.  Insulin works through the LPL enzyme and the HSL enzyme.  The LPL enzyme sends fatty acids into the cells for energy. When we exercise, LPLs trigger the release of fat from fat tissue and send those into muscle cells to burn off.  (As soon as we stop, though, LPLs work to help fat cells regain that fatty fuel, which is why Taubes claims exercise doesn’t make us lose fat, just gains us muscle.) The rest of the time, insulin triggers LPLs to send fatty acids into fat cells and tells muscle cells to burn blood sugar rather than fatty acids, so insulin basically keeps these fatty acids in your fat cells.  Insulin also suppresses the HSL enzyme, which is the enzyme that breaks down the triglycerides into fatty acids to move out of the fat cells.  And when our fat cells get full, insulin creates new ones… working constantly to make us fatter… it’s no wonder that so many diabetics that start insulin therapy gain so much weight.  Further, every other hormone in our body works to release fat from our fat tissues so that it can provide fuel for what it needs to do, but “insulin trumps the effects of other hormones.”  And as we get fatter, our demand for more fuel increases, which causes our appetite (especially for carbs) to increase. So, to lose fat, we must lower our insulin levels.  The way to do that is to diminish the cause for insulin secretion – carbohydrates.

Okay, but I eat healthy and I still struggle to lose weight, while I watch others eat fast food daily and stay super slim… frustrating, isn’t it? One reason is that “some people will secrete more insulin than others, and those who do are likely to put on more fat and have less energy.”  The other reason is that many of us have become insulin resistant. Eventually, your cells stop wanting all the glucose you’re putting in your body, and they start making insulin’s job harder to get it out of the bloodstream, which results in you secreting even more of it.  Everyone’s tissues react differently: if your muscle tissue is really sensitive to insulin, then you’ll use up more glucose in those cells, making you naturally lean, but if your fat cells are more sensitive, then glucose will go there instead and you’ll become overweight. And as we age, our muscles naturally become more resistant to insulin, which explains why we tend to get fatter as we get older.  Most importantly, this doesn’t just affect us, but our children too.. “the higher the level of a mother’s blood sugar, the more glucose her child gets in her womb” and therefore will be born with more fat and predisposition to be insulin resistant.

At this point in the book, he had my attention… is this resounding with you as well?  Tune in tomorrow for And What To Do About It.

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