A study published on September 21, 2012 in the New England Journal of Medicine concludes that the “replacement of a sugar-containing beverage with a sugar-free beverage significantly reduced weight gain and body fat gain in healthy children.” It confirms what we already should have known, that sugary beverages cause weight gain – duhhh.
Researchers conducted a double blind, randomized study of 641 Dutch children from 4 to 12 years of age. The study ran over an 18 month period. They started with healthy children who already consumed sugar-sweetened beverages and split the children into two groups.
The researchers provided each child with one can per day of an 8 ounce non-carbonated beverage. Those in the first group received a can that contained 26 grams of sugar. The second group received a can with 34mg of sucralose and 12 mg of acesulfame potassium (sugar-free sweeteners). The beverages were formulated to taste exactly the same – none of the kids knew if they were getting the sugary drink or the sugar-free one.
A number of measurements were taken of the children at the conclusion of the study, the primary of which was the “BMI z” score which measures how far away each participant’s BMI was away from the average for the child’s age and sex.
At the end of the study, the BMI z score increased 0.02 Standard Deviations for the sugar-free group vs 0.15 Standard Deviations for the sugar group. Weight gain for the sugar free group was 6.35 kg for the sugar-free group vs. 7.37 kg for the sugar group. (Remember that these are young kids who are growing, so weight gain is expected.) Both the differences in BMI z score and in the weight gain are statistically significant, proving that the regular intake of sugary beverages is causing weight gain.
How Does Sugar Cause Weight Gain?
The study authors speculate that sugar-free group gained less weight for two reasons:
1. The removal of liquid sugar did not cause the kids to be any more hungry – by removing the sugary calories and by not replacing them with other foods, fewer calories were taken in each day.
2. “The reduced ingestion of liquid sugar reduced the insulin spike and thus diminished hunger."
While I agree with both of these ideas, I’d like to unpack the second, as it forms the basis for the diet and exercise plan I created on the www.snappy-weight-loss.com website.
The Human Digestive System
To see how the dietary intake of sugar affects weight gain, we need to take a look at the human digestive system. When you eat, your body breaks down the food into certain chemical components. To look at it simplistically, it breaks down protein into amino acids and breaks down carbs (including sugar) into glucose. The amino acids are used to build and repair bones and muscles, and your blood carries glucose to every cell in your body where it’s used as fuel.
Too Much Glucose = Too Much Insulin
The problem starts when you eat a high sugar or high carb meal, and the body produces a lot of glucose. The body attempts to regulate the amount of glucose in the blood stream by using a hormone produced by the pancreas called insulin. Your muscle cells can take the glucose in your bloodstream and turn it into energy, however insulin is necessary to allow the glucose into the cells.
I think about it like this–your muscle cells have many locked doors on their surface and in order to open one of the doors and allow the glucose in, a key (the insulin molecule) must unlock that door and open it up. So when everything is working correctly, the pancreas secretes insulin and the glucose enters your cells and provides you with an energy source.
Too Much Insulin = Fat Production
The problem is that the musculature of an average adult can only hold so much glucose (100-150 grams on average). When a muscle cell is at its glucose capacity, it becomes insulin resistant and doesn’t allow its doors to be opened any longer.
When all of the muscle cells become full of glucose, the glucose and insulin continue to circulate in the bloodstream — the body can’t easily get rid of it. The way that it’s forced to remove that excess glucose from the blood is by having the liver turn the sugar into triglycerides where it can be carried back through the blood stream and eventually become deposited as a new fat cell.
Fat Begets Fat
The fat cells carry their own insulin locked doors which take much longer to become insulin resistant than muscle cells, so the next time that excess glucose enters the bloodstream, the fat cells can now take in the glucose and add to the size of the fat cell. When both fat cells and muscles are at capacity, it works the same way as described earlier, the extra blood in the glucose runs through the liver and additional fat is created and stored.
This is why those who are overweight find it so easy to gain more weight, find themselves ravenously hungry shortly after finishing a meal, and have a general lack of energy. Most of what they are eating is going to fat storage, rather than going to energy production.
The study referenced above proves that sugary snacks causes weight gain. The key to weight loss is to reduce the amount of sugar (and other carbs) eaten and to periodically empty the glucose reserves in the muscles by exercising in an intense manner. These actions will allow your metabolism to get back to a normal state where it can effectively burn what you eat for energy .
The easiest way to reduce your intake of sugar is to ditch the soda-pop. Good luck on your weight loss efforts.
Ken Stevenson is a regular guy (a manager for a Chicago-based bank) that researched a ton to determine how weight gain occurs. He shares his findings on his website, www.snappy-weight-loss.com