“Calories in, calories out” or “A calorie is a calorie” are sentences that you might have heard plenty of times if you have ever decided counting macros as a weight loss strategy.
First things first. Calories In, Calories Out is based on the first law of thermodynamics; you can’t create or destroy energy (yes, calories are energy), you can only change it. This sentence means that if you eat more energy than you need for your activity, the energy gets converted and stored as fat. Logic right?
The problem is that your body is not that simple. Your body does not “think” just in term of calories, and where those calories come from and the nutrients your food contains is very important. If the premise of calories in, calories out were true, then eating 1000 calories of sugar and 1000 calories of fat would produce the same results. Unfortunately for all of the sugar addicts out there, this simply doesn’t play out in real life.
Fat, carbs, and protein (macronutrients) all influence hormones in different ways. For example, non-fiber carbohydrates trigger the release of insulin where fat does not. Insulin is a hormone that pushes nutrients into cells, stabilizes blood sugar, and stores fat. It’s a vital hormone that has a unique side effect. It also has the ability to become disordered, resulting in insulin resistance and type II diabetes*. When hormones are out of balance, the body holds on to excess fat, weight gain becomes easier, and stored nutrients can’t be utilized. When some hormones become disordered they can disorder others as well, causing additional issues**.
And there is a study that demonstrated this***. Dr. Robert Lustig, from the department of pediatrics at the University of California, San Francisco, published a paper in 2015 where he and his colleagues believe they have come up with the definitive evidence that sugar, as Lustig says, “is toxic."
Lustig carried out a study where participated 43 children aged eight to 18 years old. He collected detailed food questionnaires from each of the adolescents to get an idea of the average amount of calories they ate per day, and designed a special menu for each of them for nine days with the same amount of calories. The only difference was that most of the sugar the children ate was replaced by starch. The children weighed themselves daily, and if they were losing weight, they were told to eat more of the provided food in order to keep their weight the same throughout the study.
“Everything got better,” said Lustig. Some of the children went from being insulin resistant, a precursor state to developing diabetes, in which the body’s insulin levels can no longer keep up with the pace of breaking down sugar that’s coming in from the diet, to insulin sensitive. After nine days of having their total dietary sugar reduced to 10% of their daily calories, their fasting blood sugar levels dropped by 53%, along with the amount of insulin their bodies produced (since insulin is normally needed to break down carbohydrates and sugars). Their triglyceride and LDL levels also declined and, most importantly, they showed less fat in their liver.
While there has been a lot of attention on the presence of belly fat and its connection to metabolic syndrome, the fact that the children saw improvements in the amount of fat in their liver suggests that might be an important way that sugar is contributing to chronic disease.