This is part two of a three part series on what the best diet is. In part I, I briefly went over the major dietary variants found in research and rattled off some of the research in support of them. Despite each diet having their own set of benefits–with many overlapping each other–they’re all running for ‘best diet candidacy’. In this part, I will go over a few general factors that determine whether one diet will work better than another.
THE OMNIPOTENT CONNECTION—LIFESTYLE AND PREFERENCES
I hope all of this is connecting. If each diet has the potential to be the best, then it doesn’t matter which diet you’re on, right? That’s half true. In each study, you will have people who do not respond as well as others, because of… individual differences. Results of studies are averages and do not explain in full why some people saw better results than others. If that is the case, then it might be better for you to look at these studies, figure out which diet may suit your condition better, and experiment. That is probably the way to go. To boot, there are very smart doctors and researchers who also agree that the best diet for you is the one that fits your lifestyle and metabolic condition.
Yes, in the realm of nutrition, you are a special snowflake. Source
Indeed, large-scale experimental, observational, and free-living studies have been conducted comparing diets with differing macronutrients to each other. Although many of the studies above show that one diet may be superior to another, there also exists research showing that differing macronutrient composition may not matter depending on the situation. One such situation is weight-loss. In light of this statement, it is sound logic to re-consider the previous theory if there is a refuting scientific result.
Back in 2007, Gardner et al published a study that would send ripples through the wide ocean of diet research. They showed that the Atkins (low-carbohydrate) diet resulted in more weight loss and more favorable blood lipids than the Ornish (vegetarian, low-fat), ZONE (balanced, mixed), or LEARN (lifestyle-based, low-fat, mixed) diets. Even at 12 months, the Atkins diet held steady. Two elephants in the room here: 1) mean weight loss between Atkins and the second best diet was 4 pounds (not a whole lot in the grand scheme of things); and 2) at two years, participants in each of the four groups saw non-statistically significant differences. In other words, the Atkins diet was no longer more effective than the other three diets at two years (Gardner, 2007). What does this tell us?
Sustainability is the ultimate trump card. It’s the deciding factor between “(weight) losers” and losers. And it’s also the one thing that will keep the results coming like rain during monsoon season in Thailand. It can be what makes any diet the best.
One of the most cited studies comparing of the effects of different diets on weight loss was published in the New England Journal of Medicine in 2009. They concluded:
“Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.” (Sacks, 2009)
Here is another study from the well-known and respected Journal of the American Medical Association. The authors summed up their findings as such:
“Significant weight loss was observed with any low-carbohydrate or low-fat diet. Weight loss differences between individual named diets were small. This supports the practice of recommending any diet that a patient will adhere to in order to lose weight.” (Johnston, 2014)
And in another study published in PLoS One, Naude et al concluded that:
“Trials show weight loss in the short-term irrespective of whether the diet is low CHO or balanced. There is probably little or no difference in weight loss and changes in cardiovascular risk factors up to two years of follow-up when overweight and obese adults, with or without type 2 diabetes, are randomised to low CHO diets and isoenergetic balanced weight loss diets.” (Naude, 2014)
Finally, Foreyt et al put their conclusion rather nicely:
“Although “a calorie is a calorie” under the controlled conditions of a metabolic unit (i.e., only the level of calorie intake matters and not the source of calories), we conclude that these interrelationships are far more complex in the free-living situation. The different diet-related factors that condition energy balance, including total energy intake, satiety and hunger sensory triggers, and palatability, must be considered when assessing the efficacy of weight-reducing diets of different macronutrient composition.” (Foreyt, 2009)
In terms of weight-loss, the evidence is stacking in favor of a simple message: as long as you stick to a reduced-energy, weight-loss focused diet where you won’t feel like killing yourself, the dietary composition of carbohydrate, protein, or fat really don’t matter.
The above bolded statement literally means you can eat Twinkies all day and lose weight as long as you’re in a calorie deficit. But let’s get a couple of things straight, it doesn’t take a nutrition researcher to know that this won’t do any favors for your health. And if your health begins to decline, then losing weight is nothing but an afterthought in the wake of suboptimal performance in daily life, metabolism decline, and horrible quality of life.
Unless of course you’re like this. Source
What applies to weight-loss also applies to other goals. Subjects in these weight-loss studies volunteered and signed up because their goal was probably to lose weight. What about if you want to gain weight? Same story here—to gain weight, you must be in a caloric surplus regardless of macronutrient composition. For the purpose of this post, this is as simple as it gets.
What about performance? Simply put, it probably doesn’t matter, either… at least not until you become an elite athlete. At that point, you will probably have to fine tune things. No one has done a case study on him, but I highly doubt Michael Phelps eats like a normal human being. He probably eats like ten normal human beings.
After all, eating food does not just serve to keep you alive, but also to make you thrive. Don’t put low-octane gas into a high-octane car.
THE METABOLIC CONDITION CONNECTION
On the other hand, this may not apply if you have a certain medical condition that precludes the weight-loss. Like lifestyle preferences, metabolic, or medical, conditions are something that must be heavily considered when following a diet. Food can be an awfully powerful drug that if abused can lead to undesirable consequences. This is why Hippocrates, the founder of Western medicine, said,
For instance, your risk of becoming diabetic is increased exponentially if you’re obese, and as much as losing weight greatly benefits diabetes management, the effectiveness of the diet can be determined by the macronutrient content. In the particular case of diabetes, losing weight is extremely helpful, but research on this front shows that low-carbohydrate diets outperform all others consistently in terms of glycemic control and lead to better weight loss than low-fat diets because of that glycemic control. Additionally, Feinman et al showed in their massive review that lower-carbohydrate diets are the most effective in terms of rates of diabetes remission and cessation of diabetes medications (Feinman, 2015).
There are other medical conditions that are affected by nutritional modulation. Non-alcoholic fatty liver disease, cardiovascular disease—high triglycerides, hypertension, suboptimal cholesterol levels—renal disease, and inflammatory bowel diseases represent just a small handful of disorders that is influenced by nutrition. Undertaking medical nutrition therapy on your own is ill-advised, so seeking out the help of someone who is licensed to proctor this type of stuff to tailor an eating plan based on lifestyle preferences, goals, and medical conditions is the best bet.
Stay tuned for the next and final installment of this series.
As always, I value your opinion. What kind of diet best suits you? How long have you been on your favorite diet?