Which of these do you believe about obesity?
- is a problem where people simply eat too much and don’t exercise enough
- is due to a slow metabolism
- is an obscure hormonal imbalance
- is the physical expression of a mental problem
- is a moral failure resulting in overeating and getting fat
NONE OF THESE ARE COMPLETELY TRUE!
As Stephen Guyenet, Ph.D. explains in his book The Hungry Brain: Outsmarting the Instincts That Make Us Overeat, obesity is more due to certain brain systems that influence our overeating of the wrong stuff, causing us to gain weight.
A powerful internal control system
First off, the body is remarkable at how tends to keep body weight stable despite a wide variation in daily calorie intake over a short term. One of the earliest studies was the Minnesota Starvation Experiment conducted by Ansel Keys in the 1940’s. In this six month experiment, volunteers lost about one-quarter of their initial body weight through semi-starvation. Subsequently, when allowed to eat as they pleased, they regained weight close to their original weight.
In a 1992 study, both lean and overweight volunteers were overfed by 50% to see what happened. They overate for six weeks, then were monitored for six weeks. All did gain weight, but as soon as the overfeeding stopped, everyone automatically and quickly returned to their original weight. Some internal control system certainly was at work here too.
A take-home point is that the set point of your weight can do down with food restriction, and it goes right back up with a return to previous ways of eating.
The kind of food matters
Pleasure from food is a sign that the brain values it as a food to ensure continuation of the species. The most pleasurable foods tend to be dense in calories, easily digested, and combine several food tastes in a highly concentrated form. This is the formula for ice cream, cookies, french fries, potato chips, pizza, bacon, and chocolate bars. Most fast food is formulated this way, as well as standardized prepared food that is heated up and served in chain sit-down restaurants.
These are the foods that affect the brain so that it craves them, leading to a loss of control over eating. Eating them is exceptionally rewarding to the brain. It is these highly rewarding foods that tempt us to end without end.
The 2010 USDA Dietary Guidelines for Americans reported that the following foods were the top calorie sources for most US adults:
- Grain-based desserts: cake, donuts, cookies
- Yeast breads
- Chicken and chicken mixed dishes
- Soda / energy / sports drinks
- Alcoholic beverages
- Pizza
Traditional diets from many cultures tend to be the opposite in they bring less intense pleasure and are less calorie dense, including more fiber.
Convenience
Food has become more convenient as the time and effort it takes to obtain and prepare it decrease with our current food system. With the rise of food processing, we get ultra-convenient food options at the grocery store. Even more convenient is fast food which we can eat with our hands and not even have to leave our cars!
Our brain is wired to go for a good deal when we see it. It is convenient. It is rewarding. Also, it is cheap. So we eat it. Without reserve.
Double Trouble
Dr. Guyenet’s hypothesis to why we gain weight and are obese involve brain networks and signalling hormones.
Leptin is a hormone produced by fat cells that acts in the brain to regulate a complex system by stopping hunger. The part of the brain that regulates body fat and appetite that functions like your home thermostat is the hypothalamus. This regulation system is called the lipostat.
When we are surrounded by high-reward convenient foods that are calorie dense, we tend to overeat them. We are programmed to go for them. The high-reward value increases the set point of the lipostat, which further increases overeating. This is the first trouble-maker leading to obesity.
Then overeating results in a spike of leptin levels. This results in damage to the hypothalamus, so it cannot be as responsive to leptin. Therefore, it needs more leptin, produced by fat cells, to tell us to stop eating. That means the set point is higher, and we maintain a higher body weight. This is the second trouble-maker.
What’s the answer?
Dr. Guyenet puts forth a six step strategy for outsmarting the hungry brain. It involves making it optimal for the brain to not get into double trouble like described. It involves awareness of what can cause us trouble and then managing our lifestyle to avoid it. In my next blog, Outsmarting the Hungry Brain, I outline these steps and emphasize its importance.
Go ahead and comment below about your take on obesity and what you have done to stay healthy.
