When browsing through social media sites, I always get amused by the nearly religious discussions about which diet is the best diet. It’s not really surprising that this is a frequent discussion topic. In the United States, more than 2/3 of the population is overweight or obese; over 60% of Americans are trying to lose weight; and nearly 50% of us are currently following a weight loss plan. Despite all our efforts, the numbers keep getting worse. One consequence of not being able to curb obesity rates is that new diets pop out virtually monthly. The pineapple diet, the Hollywood diet, low fat diets, low carb diets, the paleo diet, the mediterranean diet, Atkins diet, and on and on. Of course, they all claim to work, and promise decreased weight and waist line, better health, blood pressure under control, and a long list of more or less serious claims. But how do we go through all this? How do we choose? The goal of this article is to make some sense of what the current literature shows. However, it’s not a research paper. I am not proposing a hypothesis that I am testing with a test group, a control group, etc. It’s not a literature review paper either, although it could become the basis for one in the near future, whenever I actually get the time to do this. What I really wanted to do was a somewhat informal analysis of the literature, and pointing out commonalities.
The low carb diets
The two most popular low carb diets are the Atkins diet, created by Dr. R. Atkins over 40 years ago now, and the more recent paleo diet, founded by Dr. L. Cordain. The Atkins diet general guidelines are: very limited carbohydrates mostly as a select few green vegetables, no alcohol, no coffee, no nuts, seeds, grains, fruits, bread, pasta or dairy (aside from butter, cream and cheese). Cheese and no bread?! OK, what about the paleo diet? If you’re reading this article, I am certain you’ve read a lot about the paleo diet. Its fundamental premise is that our GI tract has not had the time to adapt to agricultural developments, grains, etc. because 10,000 years aren’t enough. Let’s ignore the fact that Dr. Cordain must not have taken a course in evolutionary biology, and let’s focus on what is recommended: lean meats, fish, poultry, all of them wild (no farm fish, grass-fed cattle only, etc.), fresh fruits and veggies, nuts, berries (wild), and basically nothing processed. Definitely no dairy products, grains (or few), coffee, or alcohol. And it’s conveniently surfing on the gluten-free craze. So, forget this:
The plant-based diets
Depending on your tastes, you may find the plant-based diets more or less drastic. Vegan and vegetarian diets recommend no meats, eggs, dairy product etc. depending on whether you go vegetarian or vegan. It can be a bit tricky as animal products end up in unexpected places. And then we have the Mediterranean diet, based on the diets adopted by Southern Italy, Greece, the East coast of Spain, etc. focusing on olive oil, fresh fruits and veggies, non-processed cereals, legumes, fish (not farmed), dairy products, and a low amount of meat. OK, bread and cheese! I can breathe.
The current guidelines
But what are the current recommendations of the various medical and federal organizations that are trying to curb the obesity epidemic? According to the American Heart Association, the Centers for Disease Control, the Food and Drug Administration and the National Institutes of Health, the recommendations for weight loss can be summarized as: balance energy input and ouput, favor fresh fruits and veggies, low fat diary products, whole grains, limit processed foods, in particular refined sugars, and move!
The really cool thing is that all these approaches have all been evaluated for several years (although some lack a long-term evaluation). And here is the funny thing: they all work, although there is still some discussion about the low-carb diets and the long term effects of ketones. Frassetto et al. show that even a short-term follow up of a paleo type diet improves several biological markers without necessarily seeing any weight loss. Jönsson et al. show that a paleo type diet reduces cardiovascular risk factors compared to more traditional DM diet in type-2 DM patients. There is also evidence of reduction of symptoms for a variety of autoimmune diseases (rheumatoid arthritis, celiac, etc.) under a paleo type diet or under an Atkins type diet. And both diets are shown to be effective weight loss methods.
When it comes to the plant-based type diets, the results are very similar. Kahleova et al. show an improved insulin response, loss of visceral fat, and improved oxidative stress markers compared to the typical DM diet. Kjeldsen-Kragh and Hänninen et al. show that vegan diets improve the pain perception of rheumatoid arthritis symptoms. Esposito et al. have shown that ‘Mediterranean-style diet might be effective in reducing the prevalence of the metabolic syndrome and its associated cardiovascular risk.’
So, that’s really interesting. They all suggest vastly different foods, yet they all yield extremely similar results. Why is that? Here is a really interesting quote from Pagoto et al.
In the past year alone, 4 meta-analyses of diet comparison studies have been published, each summarizing 13 to 24 trials. The only consistent finding among the trials is that adherence—the degree to which participants continued in the program or met program goals for diet and physical activity—was most strongly associated with weight loss and improvement in disease-related outcomes. The long history of trials showing very modest differences suggests that additional trials comparing diets varying in macronutrient content most likely will not produce findings that would significantly advance the science of obesity. Progress in obesity management will require greater understanding of the biological, behavioral, and environmental factors associated with adherence to lifestyle changes including both diet and physical activity.
Aha! So what seems to work is essentially…sticking with the plan!
Additionally, all the diets mentioned above all recommend to stay clear of processed foods, refined sugars, refined grains, they all recommend quality foods: if you eat beef, make sure it’s fed what it’s supposed to eat; if you eat fish, make sure it has swum a bit farther than your local fish farm; if you tomatoes, make sure it’s round and in the veggie section of your grocery store, and not in a plastic bottle with ketchup written on it. The commonality of all these diets (besides the positive health outcomes) is: quality! Note however that this hasn’t been evaluated in a scientific manner, e.g. there hasn’t been a study looking at the quality of the food and the outcomes on health, at least not in a systematic and scientific manner.
All in all: eat quality food, avoid processed foods as much as possible, and the rest is really a matter of preference, but provided you stick to your plan, balance energy input/output, eat well, move well, you’ll be just fine regardless of which (sensible) diet you choose.
1. Frassetto et al., Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet, European Journal of Clinical Nutrition, February 2009, v.63, pp947-955.
2. Jönsson et al., Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study, Cardiovascular Diabetology, July 2009, v.8(35).
3. Kahleova et al., Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes, Diabetic Medicine, May 2011, v.28(5), pp549-559.
4. Hänninen et al. Antioxidants in vegan diet and rheumatic disorders, Toxicology, Nov. 2000, v.155(1-3), pp45-53.
5. Kjeldsen-Kragh, Rheumatoid arthritis treated with vegetarian diets, The American Journal of Clinical Nutrition, Sept. 99, v.70(3), pp594-600.
6. Esposito et al., Effect of a Mediterranean-Style Diet on Endothelial Dysfunction and Markers of Vascular Inflammation in the Metabolic Syndrome, Journal of the American Medical Association, Sept. 2004, v.292(12).
7. Pagoto et al., A Call for an End to the Diet Debates, Journal of the American Medicial Association, Aug. 2013, v.310(7).