Are all calories the same? Is the obesity epidemic a result only of too many calories combined with too little exercise? Dr Robert Lustig, a professor of clinical pediatrics at the University of California (San Francisco), does not think so.
If one’s weight really is a matter of personal responsibility, how can we explain toddler obesity? Indeed, the US has an obesity epidemic in six-month-olds. They don’t diet or exercise. Conversely, up to 40% of normal-weight people have chronic metabolic disease [including diabetes, heart disease, cancer, and dementia]. Something else is going on.
Consider the following diets: Atkins (all fat and no carbohydrates); traditional Japanese (all carbohydrates and little fat); and Ornish (even less fat and carbohydrates with lots of fiber). All three help to maintain, and in some cases even improve, metabolic health, because the liver has to deal with only one energy source at a time.
That is how human bodies are designed to metabolize food. Our hunter ancestors ate fat, which was transported to the liver and broken down by the lipolytic pathway to deliver fatty acids to the mitochondria (the subcellular structures that burn food to create energy). On the occasion of a big kill, any excess dietary fatty acids were packaged into low-density lipoproteins and transported out of the liver to be stored in peripheral fat tissue. As a result, our forebears’ livers stayed healthy.
Meanwhile, our gatherer ancestors ate carbohydrates …. So their livers also stayed healthy.
And nature did its part by supplying all naturally occurring foodstuffs with either fat or carbohydrate as the energy source, not both. Even fatty fruits – coconut, olives, avocados – are low in carbohydrate.
Our metabolisms started to malfunction when humans began consuming fat and carbohydrates at the same meal.
Robert H. Lustig “The Diet Debacle“, Project Syndicate, 28 May 2012.
What about sugar? This, according to Dr Lustig, is a dangerous poison. The only healthy way to eat sugar is to consume fruit, which contains sugar, but also the antidote: fibre. When juice is extracted from the fibre, it is no longer healthy. The same (alas) is true of wine, and all alcohol. Excess consumption of sugar is a major reason “33% of Americans have a fatty liver, which causes chronic metabolic disease”. Honey, by the way, contains no fibre, so is just as unhealthy as cane or maple sugar. For more information on sugar in your diet, go to Happy Healthy Long Life.