How Diet Affects Gene Expression
A new study from the Norwegian University of Science and Technology – Trondheim has mapped the way that diet affects gene expression. Gene expression is the “process where information from a gene’s DNA sequence is translated into a substance, like a protein, that is used in a cell’s structure or function.”
The study found that different types of foods cause different reactions in the cells themselves. Some of these reactions are considered good, and some are destructive, leading to increases in inflammation. As Dr. Steve Parker has noted, inflammation is thought to have a role in developing atherosclerosis (the cause of heart attacks and strokes), type 2 diabetes, and some cancers.
Bad News for Calories In/Calories Out
The idea that a “calorie is a calorie” and that the secret to losing weight and a healthy lifestyle is “eat less, move
A "bomb calorimeter" is used to determine the calories in food
more” assumes that all food is equal. The solution for a calorie counter is to simply induce a “calorie deficit” by burning more energy than you eat. When you have a calorie deficit of 3,500, you lose a pound of fat. This approach does work for some people, most notably young, healthy males, but rarely works as well for those in middle age. And women have an especially hard time losing weight this way.
As I noted in Eating Fat Does Not Make You Fat, it does matter what foods you eat. In that article we show that in every single test of a low carb vs. low fat diet, the low carb group has no calorie restriction. Yet they lose more weight, faster, than any other diet. The low fat diet proponents claim the low carb diet folks are “cheating” by spontaneously eating fewer calories.
This new study should put the final nail in the coffin for “calories in / calories out” mantra from a health perspective. It does matter what you eat, even more than how much you eat.
How The Study Was Conducted
The main study included 28 slightly overweight men and women who ate two different powdered diets. This type of controlled study on actual people, rather than a meta-analysis of statistics from other studies, shows actual cause-and-effect of the different diets for this group of men and women. A “cleansing period” of a week allowed the participants to eat normally between the diets. The researchers had the participants drink the liquid diet six times a day, with each participant’s caloric intake calculated to maintain their current weight.
The first powdered diet provided 65 percent of the calories from carbohydrates, 15 percent from protein and 20 percent from fat. For a 2,000 calorie diet, that’s 1,300 calories from 325 grams of carbohydrates, 300 calories from 75 grams of protein, and 400 calories from 44 grams of fat. That is very close to the USDA recommendations for a “well balanced diet”.
The second powdered diet provided calories close to one-third carbohydrates, protein and fat. For our 2,000 calorie diet, that would translate into 667 calories for each macro-nutrient, with 167 grams each of carbohydrates and protein, and 74 grams of fat.
Blood tests were conducted before and after each diet period. All of the measurements of changes in gene expression were done so that each individual’s difference in gene expression was compared with that person alone. The results were then compiled.
Johnson says the studies resulted in two important findings. One is the positive effect of many meals throughout the day, and the details about the quality and composition of components in an optimal diet, including omega-3 and omega-6 fatty acids. The second is that a carbohydrate-rich diet, regardless of whether or not a person overeats, has consequences for genes that affect the lifestyle diseases, she says.
It’s important to remember that this is not a weight loss study, as the liquid diets were carefully measured to keep the participants at a steady weight. This prevents the temporary “bad effects” of weight loss from showing in the blood samples (those effects are explained clearly by Dr. Davis in his post about the alarm some dieters have after losing weight and seeing blood test results).
What the Study Found
For many health issues, there isn’t a single controlling gene. The researchers had to compare multiple genes to see how they reacted to the different diets. The article quotes professor of biology Berit Johansen:
“We are talking about collecting a huge amount of information,” says Johansen.
“And it’s not like there is a gene for inflammation, for example. So what we look for is whether there are any groups of genes that work overtime. In this study we saw that an entire group of genes that are involved in the development of inflammatory reactions in the body work overtime as a group.”
The lower carbohydrate diet not only reduced inflammation, but reduced activity of the genes associated with type 2 diabetes, cardiovascular disease, Alzheimer’s disease and some forms of cancer.
“It was interesting to see the reduction in genetic activity, but we were really happy to see which genes were involved. One set of genes is linked to cardiovascular disease. They were down-regulated in response to a balanced diet, as opposed to a carbohydrate-rich diet,” she says. Another gene that was significantly differently expressed by the diets that were tested was one that is commonly called “the youth gene” in the international research literature.
“We haven’t actually stumbled on the fountain of youth here,” Johansen laughs, “but we should take these results seriously. The important thing for us is, little by little, we are uncovering the mechanisms of disease progression for many of our major lifestyle-related disorders.”
Problems with the Article
The article shows that the idea of “calories in / calories out” is at best a simpleton’s approach to healthy eating, as it ignores the micro-nutrient composition of the foods we eat. It also provides direct evidence that the low fat diet is dangerous even though it is often prescribed as a way to reduce cardiovascular heart disease and presented as the “healthy alternative” to the standard American diet. But the good professor veers off the rails with some unsubstantiated advice:
The professor warns against being caught up in the fat trap. It’s simply not good to cut out carbs completely, she says. “The fat/protein trap is just as bad as the carbohydrate trap. It’s about the right balance, as always.”
She says we must also make sure to eat carbohydrates, proteins and fats in five to six smaller meals, not just for the main meal, at dinner.
“Eating several small and medium-sized meals throughout the day is important. Don’t skip breakfast and don’t skip dinner. One-third of every meal should be carbohydrates, one-third protein and one-third fat. That’s the recipe for keeping inflammatory and other disease-enhancing genes in check,” Johansen explains.
The problem with this portion of the article is that there is no evidence presented for her claim that a “balanced” intake of the three macro-nutrients is better than a lower carb variant. The study tested only a high carb / low fat diet against a lower carb diet. In order to make the claim above she would have to actually test the hypothesis that getting one-third is better than getting one-fifth of your calories from carbohydrates, as a typical 100 gram per day “maintenance level” low carb diet would provide. While there’s always the possibility that the professor has done such as study, and her statement is based on that prior study, I suspect she is “thinking linearly”. She really has no way to conclude that one-third carbohydrates is better than one-fifth carbohydrates until she tests it.
The study does provide direct evidence that the diet advice given to the American people by the USDA, that 65 percent of their calories should come from carbohydrates, is actually dangerous. Rather than reducing the risk for cardiovascular disease, type 2 diabetes, Alzheimer’s disease and some forms of cancer, the high carbohydrate diet “turns on” the genes associated with those chronic health problems.
The article also does not provide a citation for the idea that eating six times daily is better than three or four times (more frequent meals are usually recommended in higher carb diets to try and control the wild blood sugar spikes that occur). Many paleo / primal dieters find that eating “when hungry” leads them to fewer meals, often only two, in a typical day.
It Could Work
Even with my reservations, having someone adopt a true “balanced diet”, with one-third of their calories from carbohydrates, protein and fat, would undoubtedly lead to better health than the Standard American Diet. If the goal is to lose weight, reducing carbohydrates further, to 20 percent of total caloric intake, will usually result in slow, steady weight loss. To lose weight at the rate of 1 to 2 pounds per week, a true low carbohydrate diet, below 50 grams of carbs per day, will result in the best results for most people.