After several hints that gut microbes may be key players in the obesity epidemic, a new study provides a mechanistic explanation of how the intestinal inhabitants directly induce hunger, insulin resistance, and ultimately obesity in rodents.
This study shows that there are more stem cells available in the gut when fed a high fat diet. To jump from evidence of greater stem cell abundance/activity straight to cancer is what most would call “Story Time”. Story time is when researchers start to speculate wildly and pretty much divorce themselves from the data whenever it suits them. Great for brainstorming new things to research, but it should never be the basis of entire news articles for the layperson who cannot differentiate between pure speculation and what the evidence actually says.
An alternate explanation (and one I personally feel to be more in line with basic biology) is that the high fat diet is overall less stressful on the gut, thereby sparing stem cells from having to repair as much damage day-to-day, and thus resulting in greater available un-utilized stem cells for these researchers to detect and manipulate. The metabolism of the intestine is fueled primarily by the catabolism of carbohydrates and carbohydrate precursors like amino acids. Fat largely bypasses the enterocyte to enter the lymph system (the degree to which this happens depends on fatty acid chain length in most species, so the point raised by others regarding the type of fat is very important) to be metabolized first not by the gut but by the liver. Higher fat diets mean lower carbohydrate and/or protein (protein being made of amino acids, many of which can be used to synthesize carbohydrates when catabolized), and as we all know higher carbohydrate diets have been tenuously linked with all sorts of pro-oxidation metabolites and indices of poor gut health like inflammation. Things that would require a higher level of chronic stem cell utilization for repair of oxidation caused damage. This paper is more evidence of the protective effects of fat specifically on gut health, than any evidence of harm from cancer or otherwise.
Never mind the fact that this is ultimately a rodent and cell culture study. Just yesterday ARS had an article showing just why mouse model work is next to worthless as a direct extrapolation to human medicine. From that article
One of the women in the study had complete loss of function from a gene called PRDM-9, which determines where maternal and paternal chromosomes recombine (exchange genetic material) during meiosis. As far as genetic fitness of a species is concerned, this recombination is probably the single best thing about reproducing sexually as opposed to any alternative. PRDM-9 knockout mice are sterile, but this woman was not.
Genes drive our biology, and if genes of fundamental importance to mice can be essentially irrelevant to humans, we should be very careful when extrapolating evidence between the species. Even if, for the sake of argument, we assume that the authors preferred narrative is true all it really tells us is that mice should avoid a 60% fat diet, and that it might be worth looking into the effects of a 60% fat diet in humans. But then you would have to reconcile this assertion with indigenous populations like the Inuit mentioned by someone else who consume diets where essentially all of their calories come from fat, or the Masi who (the men anyway) live almost entirely on milk and blood from cattle which is also very low in carbohydrate and thus resulting in a predominance of calories coming from fat.
There’s a deep sense of irony in adding to a never-ending series of headlines on a study that shouldn’t have had any attention paid to it at all. But the publication on the dangers of the “paleo” diet that’s spawned countless headlines is so flawed that it’s worth exploring why it got so much attention.
I hate how the popular press covers nutrition and health. Popular journalism on this is a garbage fire. Its terrible.
You get dubious results like this ampped up to full volume. You get an emphasis on in individual isolated studies instead of a focus on broad scientific evidence. You get idiots like Dr. Oz and Michael Pollan taken as credible experts on things, and even given TV shows to spew their garbage. You get blatant pseudoscience that contradicts the scientific consensus taken as a credible/sensible opinion.
Genetically engineered bacteria can prevent mice offered a high-fat diet from overeating. The beneficial effects of the bacteria last for about four to six weeks, suggesting that they temporarily take up residence in the gut.
Researchers developed the anti-obesity therapy to test a new way of treating chronic diseases. Sean Davies, a pharmacologist at Vanderbilt University, is modifying bacteria that live in and on the body—known collectively as a person’s microbiome. The hope is that engineered microbes could secrete drugs to treat diabetes, high blood pressure, or other conditions over the long term, eliminating the need to remember to take a pill. Another benefit is that many drugs—including the one tested by the Vanderbilt group—cannot be administered orally because they wouldn’t survive digestion. Bacteria could make it easier to administer such drugs.
Most people who exercise or compete in endurance sports would probably answer no. For decades, recreational and competitive athletes have stoutly believed that we should — even must — consume a diet rich in carbohydrates to fuel exertion. The conventional wisdom has been to avoid fatty foods because they are an inefficient fuel source and could lead to weight gain.
But in recent years, some scientists and quite a few athletes have begun to question those beliefs. Athletes devoted to ultra-endurance sports, in particular, tout high-fat diets as a means to improve performance.
…exercise scientists long ago established that endurance training makes athletes better able to use fat as a fuel. And that metabolic adaptation prompted many scientists and coaches in recent years to wonder what would happen if you extended that ability to its farthest extreme and trained an athlete’s body to rely almost exclusively on fat, by removing almost all carbohydrates from the diet and ramping up grease intake?
If you decide to make a change – do it in the off season. It may take a few weeks for your body to adapt to a high-fat diet (three weeks for cyclists in one of the studies), and it may never work well if you’re doing sports that require sudden bursts of power or strength, like weightlifting, Crossfit, or team sports like American football. But if you’re gearing up for a marathon or a long bike race, bacon-heavy breakfasts might suit you just fine.
For vegans/vegetarians, you’ll want to source fat from the following:
Cheese (assuming not vegan/etc and/or lactose intolerant)