By Dr. Jason Fung 
Many diets are based on bad science. The real drivers of obesity are refined sugar and carbohydrates. And that’s because of their effect on the hormone that regulates many of our bodily processes: insulin.
Clearing up common misconceptions about obesity
- Obesity isn’t always caused by bad eating habits. In fact, genetic factors account for about 70% of a person’s likelihood to develop obesity.
- There is no causal relationship between calorie intake and obesity. There is correlation, but not causation.
- The calories we consume are not automatically converted to fat. Calories are used for all sorts of things like producing heat, proteins, bone and muscle tissue, fueling your brain and increasing the volume and rate of your heartbeat. Fat production is just one of many different things your body does with the calories you consume. [Ed. note: I guess this explains why I get cold so easily when on a reduced calorie diet].
- Obesity isn’t a problem caused by eating too much. Some people’s bodies convert calories into fat while others will simply develop bigger bones and muscles or use that energy to boost their concentration. Of all the things that calories are used for, only one is socially problematic.
- The reason that just reducing calories doesn’t lead to weight loss is because it lowers your metabolic rate. For instance, if you reduce your calorie intake by 30%, your body will adjust and expend 30% less energy.
- Science has determined that high insulin levels are the real cause of obesity, though the exact way this works isn’t clear. 75% of all successful weight-loss efforts can be directly attributed to reduced insulin levels. Drugs which raise people’s insulin levels result in weight gains while drugs which have the opposite effect cause weight loss.
- Insulin removes sugar from your bloodstream and deposits it in your body’s cells. When you eat sugars and carbohydrates, your body produces extra insulin to deal with them. If this goes on too long, your body’s cells become insulin-resistant and stop taking sugar from your blood. But the cells still need sugar, so they constantly cry out for more food, resulting in weight gain.
- Snacking between meals prevents weight loss because it keeps insulin levels high. Your body needs 4-5 hours of fasting between meals for your body’s insulin to return to a low level.
- Obesity and poverty are correlated because the cheapest foods the food industry produces tend to be high in white sugar and refined carbohydrates (e.g. corn and wheat), which are leading causes of insulin-resistance. One of the reasons these foods are so cheap is because the US government heavily subsides corn and wheat farmers.
- Eating too much fat does not cause weight gain. Most dietary fats are not unhealthy at all. The exception is modified trans fats which are bad for you. Most vegetable oils are fine, but vegetable oil products, such as margarine, are artificially saturated (with hydrogen) to extend their shelf life. These are called modified trans fats or hydrogenated vegetable oils. They increase bad cholesterol and decrease good cholesterol.
Another food-related misconception is that coffee is bad for you. In truth there’s more good than bad about coffee. It’s rich in antioxidants which help slow the aging process in cells, and also magnesium, which is good for your bones and heart. Studies also suggest that coffee reduces the risk of type 2 diabetes, Alzheimer’s and Parkinson’s disease.