The last couple of months have been hard on obesity experts as they have learned that maybe the obvious is not so obvious.
It started out in October with an article in the New England Journal of Medicine on the substitution of sugar-sweetened beverages with politically correct sugar-free beverage replacements (1). Everyone from Mayor Bloomberg to Dr. Oz knows that soda makes you fat. It is so obvious there is no need to confirm this “fact”. Almost out of due diligence, Harvard Medical School did a two-year study just to confirm this most obvious obesity fact that sugar-sweetened soda makes you fat. Researchers took obese adolescents, who were confirmed soda (containing evil fructose) drinkers. Half were used as the control group; the other half as the experimental group, who were sent regular supplies of “good” beverages (not fruit juices) to replace the sugar-sweetened sodas. They also got motivational phone calls on a monthly basis to urge them on and also to tell them not to watch as much TV.
It worked. At the end of two years, they were drinking fewer sugar-sweetened beverages, watching less TV, and consuming fewer calories and far less sugar than the control group. All of these changes in their lifestyles were strongly statistically significant.
So how did this affect their obesity compared to the control group? There was no difference! Maybe there were just incompetent researchers. I think not, because the research was led by one of the most respected obesity researchers in the world. Maybe the facts that were so obvious to Mayor Bloomberg and Dr. Oz were not so obvious after all.
This was bad enough, but then another article appeared in the January issue of the New England Journal of Medicine stating that we actually know virtually nothing about the treatment of obesity (2). Oh, yes, you can make a lot of correlations (like not drinking sugar-sweetened soda, eating fewer calories and watching less TV) that are associated with lower weight, but no scientific data are there to support this. In fact, the only things we can really be scientifically certain about treating obesity are gastric bypass surgery, some prescription drugs that suppress appetite (like amphetamines) and following a highly structured meal plan using meal replacements with a defined composition. These three factors cause weight loss compared to control groups.
Gee, after 30 years of our obesity epidemic (and millions of research dollars) you would think we would have some more solid scientific data. It turns out that obesity research is more like religion—don’t confuse me with the facts.
Why do we have such ignorance about what causes obesity, let alone how to treat it ? Some of the reasons come from recently published genetic studies with genetically inbred mice (3). Using more than 100 different genetically pure strains with a highly defined diet (rat food pellets), it was found that once they are switched to a high-sugar, high-fat diet that some of the genetic strains gain weight, and some don’t. In fact, the differences in fat gain were nearly 600% among different strains.
What does this mean for humans? Classical genes don’t change quickly; however, epigenetic markers that turn genes on and off can change within one generation. Here lies the problem. Our obesity epidemic is not because of making either bad food or lifestyle choices, but may be due to changes in food composition that our parents were eating that modified the expression of our genes in the womb.
The most likely suspect gene-altering drama is increased consumption of omega-6 fatty acids, such as linoleic acid, which lower the percentage of omega-3 fats in the diet (4). I described this in greater detail in my book “Toxic Fat” (5). Simply stated, in a period of 50 years, we have been become genetically altered by increasing linoleic acid to gain weight rapidly and make it difficult to lose. Those epigenetic changes will not evaporate with simple slogans found on TV talk shows or from a politician’s mouths. They will take probably three generations to return to what they were in an earlier time, and only if there is a radical restriction in the linoleic intake by humans.
Meanwhile, prepare yourself for more political (and scientific) blowhards who have all the answers to a very complex set of problems resulting from a continued modification of our genes and those of our children, making us overweight, sicker, and aging faster.
1. Ebbling CB et al. “A randomized trial of sugar-sweetened beverages and adolescent body weight.” N Engl J Med 367:1407-1416 (2012)
2. Casasa K et al. “Myths, presumptions, and facts about obesity.” N Engl J Med 368:446-454 (2013)
3. Parks BW et al. “Genetic control of obesity and gut microbiota composition in response to high-fat, high-sucrose diet in mice.” Cell Metabol 17:141-152 (2013)
4. Hanbauer I et al. “The decrease of n-3 fatty acid energy percentage in an equicaloric diet fed to B6C3Fe mice for three generations elicits obesity.” Cardio Psychiartry Neurology 2009: 867041 (2009)
5. Sears B. Toxic Fat. Thomas Nelson. Nashville, TN (2008)