Robert Lustig MD, is a name I have mentioned many times on my Facebook page and blog. He’s the sugar guy. When I came across a book written by him about sugar, processed foods, obesity, and disease, I simply couldn’t pass it up. .
Early in the book, he quickly disputes the myth that “a calorie is a calorie.” First off, he states that caloric output is controlled by your body and is dependent on the quantity and quality of the calories ingested. If you decrease the amount you eat, the body will decrease it’s energy expenditure. Second, he argues that if a calorie was a calorie, we could look at all fats, proteins, and carbohydrates the same, based on their caloric content per gram, but they don’t all behave the same way. The third contradiction is the admonishment that we are eating too much, which just isn’t true. Due to the low fat directives of the 80′s, fat consumption went down, protein remained relatively stable, and the consumption of starch and sugar, especially sugar, increased. It wasn’t that we started eating more of everything, just eating more simple carbohydrates.
Lustig believes it was not really fair to assume that because someone is obese, it means that they are lazy and overeat. A rise in blood sugar precipitates a release of insulin. Insulin’s job is to store energy into fat cells. It blocks leptin signaling which can be a bad thing. Leptin is an important protein that is released by the fat cells to signal the brain that there is enough energy stored. Unfortunately, since insulin blocks it, your brain believes that you are starving and drives you to eat more. In response to this signal of starvation, the sympathetic nervous system looks to conserve energy, keeping energy low. The vagus nerve goes into overdrive, increasing appetite, insulin, and energy storage. This leaves you feeling hungry and tired. This is probably one of the best and most comprehensive explanations of obesity that I have come across. He continues on to explain how we become addicted to substances such as sugar. The reward center in our brain releases a neurotransmitter called dopamine and it results in our experience of pleasure. To make sure that humans have the urge to eat and continue surviving, eating is a powerful reward and source of pleasure. Stress can be another factor in obesity. The hormone cortisol and the sympathetic nervous system can raise blood sugar and increase insulin production in times of stress to help a person deal with the situation. Unfortunately, many people suffer from chronic stress and prolonged exposure to cortisol. Cortisol drives you to eat, especially the consumption of energy dense foods, while insulin stores the energy.
The author continues on to talk about the two antidotes to this sugar crisis, fiber and exercise. Fiber slows the rate of food absorption in the intestine which allows the liver to fully metabolize the incoming energy without it creating a surplus. Foods that lack fiber increase your blood sugar at a faster rate and it reaches a higher peak, doing the same to your insulin levels. Fructose (sugar) is present in fruit but it is also packaged with fiber, the antidote to the sugar is already in the package, just the way nature intended. When we have smoothies or juice, we break down the insoluble fiber, thus causing a spike in our blood sugar and insulin. Exercise is the other antidote. While it’s not the best strategy for losing weight, it greatly increases your health by increasing your muscle mass. Exercise helps improve insulin sensitivity and lower insulin levels. Increasing muscle mass helps reduce the amount of visceral fat that you have. It helps prevent disease by improving your metabolic profile. It doesn’t really matter what exercise you choose, just exercise.
He touches upon quite a few things in the book. He talks about nutrition and how different nutritional approaches work and compare to each other. He also talks about how the food industry has responded to the attacks on sugar, how the government has helped create this nutritional nightmare, and what are some possible solutions. I believe this one of the best books I have read about how obesity is caused and how sugar does its damage. I plan on reading it again and referring to it many times in the future.