From a metabolic perspective (as opposed to a weight management perspective), not all calories were created equal, claimed Lustig, M.D., MSL, professor emeritus of pediatrics at the University of California, San Francisco, who has spent years arguing that sugar causes health problems unrelated to its calories and unrelated to the attendant weight gain, and that it’s possible to be overweight or even obese and healthy.
“A calorie is a unit of physics, it’s how much energy you have to add to a gram of water to raise it one degree centigrade,” explained Dr Lustig, who gave a lecture on March 9 devoted to busting “myths promulgated by the food industry for its own purposes”.
He added: “Your body is not a bomb calorimeter, it has unique biochemical reactions, and in addition, calories are measured here at the mouth, what you eat, but who cares?
“What you care about it how many calories did you absorb? So when you consume a food with fiber [for example], you actually only absorbed about 75-80% of the calories of the calories you ate. The rest of it got metabolized by the bacteria in your intestine, yet you counted them as calories so if you consume your calories with fiber, those calories weren’t for you, they were for your bacteria.
‘Your body is not a bomb calorimeter’
He explained: “In addition, different foodstuffs are metabolized at different rates. Turns out you have to invest energy to turn a protein into ATP [adenosine triphosphate, a form of energy used by cells to power our activities] as opposed to say, a carbohydrate.
“So you lose energy in the process, so there is a net energy loss compared to carbohydrates, so from a calorie standpoint, if you measure it in a bomb calorimeter, they generate the same amount of heat, but that doesn’t have anything to do with biochecmical ATP, or if it ends up raising your insulin and going into fat cells.”
Low fat vs low carb?
But for the purposes of weight management, isn’t it a case of energy in, energy out, with a recent study out of Stanford University (Gardner et al, JAMA, 2018) suggesting that a low fat diet is just as effective as a low carb diet at weight loss?
According to Dr Lustig: “The thing that’s important about that study is that the [volunteers] were [on] a healthy low carb diet and a healthy low fat diet. In other words, both groups had processed carbohydrates and sugar taken out of their diets, and that showed equal weight loss, whether it was low carb or low fat.
“So all of these people yelling at each other, you know, the vegans against the Paleos and the ketogenic people, this is insane. It’s is about real food. Both groups ate real food and got better, and that’s the takeaway from this study.”
Saturated fat… not the nutritional bogeyman?
On the issue of saturated fat, which nutrition scientists at the recent International Congress on Vegetarian Nutrition argued had “not been exonerated” by recent meta-analyses, Dr Lustig argued that it “takes a long time to walk back mistakes.”
He added: “Saturated fat is not one item, it’s two. There are meat and dairy saturated fats, and they are not the same. Red meat and poultry saturated fat is even chain fatty acids, and dairy saturated fats are odd chain fatty acids with a different phospholipid signature. Turns out that when you look at odd chain fatty acids with that phospholipid signature, that is actually protective against cardiovascular diseases, but they all get lumped into this thing called saturated fat.”
Red meat: There are potentially three reasons why red meat might be unhealthy, ‘but none of those has anything to do with saturated fat’
But when it comes to red meat, it’s not just saturated fat that is at issue when it comes to health concerns, he said.
“It is likely that red meat has very specific reasons why it is potentially more dangerous for health than other animal products, but it’s not the saturated fat.
“It could be the branched chain amino acids; it could be the iron and the heme, which generate reactive oxygen species; it could be the Trimethylamine-N-oxide (TMAO) that Stanley Hazen at the Cleveland Clinic demonstrated from the metabolism of choline by the bacteria to Trimethylamine, so there are potentially three separate reasons why red meat might be more egregious in terms of health, but none of those has anything to do with saturated fat.”
The takehome: Eat real food
So what’s his takeaway message for the food industry?
“Sell real food. Processed food is an experiment that failed. They are getting rich, and it’s killing us.”
Obese and healthy?
Asked about his contention that obesity does not cause metabolic dysfunction (cardiovascular disease, type two diabetes etc), but is a result of metabolic dysfunction, Dr Lustig responded that it was possible to be both obese and healthy.
“Absolutely, we’ve studied these people, we have a name for them, MHO, metabolically healthy obese, they have big butt fat and they do not seem to harbor any metabolic perturbations, and their telomeres are as long as those of normal weight people, so obesity is not harming them in any way.
“But of course they are a minority, they are only about 20% of the obese population and the rest are metabolically unhealthy obese.”