Paleo. Whole 30. Ketogenic. DASH. Atkins. Flexitarians. Weight Watchers. The list of diets and their various restrictions, rules, and regulations goes on and on.
The estimated 45 million Americans, who embark on one of these eating plans each year, often do so to lose weight. A highly personal process that can lead to various results. One person finds success cutting carbs, while another swears to go vegan. A third fills up on healthy fats. Each one believes (s)he has found the elusive secret to weight loss.
After discussing into details about the ketogenic diet in the first series, we dive now further to the question if there is anything like "the best diet".
The definition of diet
According to the Meriam-Webster dictionary, the definition of diet can be categorized into two main concepts. The first one is about the habitual food and drink consumed by a person as nourishment. The second one has a more specific meaning, i.e., prescribed or controlled for particular reasons such as a medical condition, or weight loss. The latter definition is typically understood and adopted by the general public, while the former one may carry a long-term health impact.
Diet as part of lifestyle
Diet is an integral part of a lifestyle, besides other things such as exercise, stress, sleeping pattern, etc. All of these factors interact with each other and affect an individual's health. For example, stress is related to unfavorable eating habits [1], and exercise is associated with stress [2]. It is hence essential to keep a healthy diet as an integral part of a healthy lifestyle while maintaining a regular exercise, coping with stress, and keeping a good sleep rhythm with sufficient quality and duration. Diet among other lifestyle factors, has been shown to affect gut microbiota [3, 4]. The effect of such lifestyle factors on the gut microbiota has even been demonstrated larger than genetic factors, keeping in mind that gut microbiota also plays an essential role in shaping an individual's trait [5].
What is the best diet?
Unfortunately, there is no such thing as the best diet. Christopher Gardner, director of nutrition studies at the Stanford Prevention Research Center and the first author of low-carb versus low-fat study [6] said that there is not any single diet that anybody has to follow.
In the first study [6], one group of people drastically reduced their intake of carbohydrates, while other slashed fat intake. But aside from that, the entire study group followed, by and large, the same advice. Everyone was told to limit added sugars, refined flours, and trans fats, while eating more vegetables and nutrient-dense foods. They also got identical guidance about healthy lifestyle habits, like sitting down to eat and cooking at home.
The other study, on vegetarian versus Mediterranean diets, had a similar results [6]. While there were some differences between the two plans, both groups of people ate mostly whole grains, legumes, and nuts -- and saw similar reductions in risk factors for heart disease.
Differences in dietary responses have been observed [7, 8]. Gut microbiota, among other factors, has been suggested to determine such variations [8], but gut microbiota is highly personalized and associated with metabolic health [9]. Therefore, defining the best diet for one person may be different from others [7, 10], calling an effort to formulate a diet that works well for each person or personalized nutrition. It is an emerging field at this moment, with much effort poured into this area.
Dr. David Katz, the founding director of Yale University's Yale-Griffin Prevention Research Center, concluded that, in fact, whole foods, close to nature, mostly plants, are good for people, and it never changes [11]. It is fundamental truth we are not willing to accept. Part of the problem, Katz says, is public confusion. New eating plans and "superfoods" are continuously cast as the keys to health, and consumers can feel overwhelmed by choice and information.
The food industry, on the other hand, constantly streams new products and nutrition gimmicks. It makes them part of this confusion. Not only them, researchers who set out to find something novel simply to generate publicity hold the same responsibility in creating public confusion that makes it seem like we don't know much about nutrition. When a headline on Monday says carbs are bad, and a story on Wednesday says they are good, people toss up their hands and say, "While they fight it out, you can find me at Burger King."
When you cut through the headlines, marketing campaigns and studies, you will find that most experts agree on a few fundamentals of nutrition: that vegetables, fruits, whole grains, beans, lentils, nuts seeds, and plain water should make up the majority of what people eat and drink. Such healthy plant-based diet with little consumption of red and processed meat seems the most promising diet based on the collected evidence on epidemiological studies and clinical trials [12, 13]. Of course, the formulation of such a healthy plant-based diet depends a lot on the geographical region [14], such as the Nordic diet in North Europe, the Mediterranean diet in the Mediterranean countries, or DASH diet in the USA.
Conclusion
Because people vary a lot in their response to different diets, an effort to formulate personalized nutrition in the future is emerging. Therefore, there is no such thing as "the best diet" at this moment, since one person will respond differently to the same diet. The collected scientific evidence nominates a healthy plant-based diet with little consumption of red and processed meat as "the recommended diet", but the exact composition differs a lot by regions. Overall, though, healthy diets largely resemble one another and contain significant overlap even among the "competing" plans [6]: vegetables, fruits, whole, grains, beans, lentils, nuts, seeds, and plain water. This composition seems to be more critical than debating whether low-carb or low-fat is better, likewise vegetarian or Mediterranean diet.
S.A.D Team
Reference
Järvelä-Reijonen E, Karhunen L, Sairanen E, Rantala S, Laitinen J, Puttonen S, Peuhkuri K, Hallikainen M, Juvonen K, Myllymäki T. High perceived stress is associated with unfavorable eating behavior in overweight and obese Finns of working age. Appetite 2016;103:249-58. doi: 10.1016/j.appet.2016.04.023.
Föhr T, Tolvanen A, Myllymäki T, Järvelä‐Reijonen E, Peuhkuri K, Rantala S, Kolehmainen M, Korpela R, Lappalainen R, Ermes M. Physical activity, heart rate variability–based stress and recovery, and subjective stress during a 9‐month study period. Scandinavian Journal of Medicine & Science in Sports 2017;27(6):612-21. doi: 10.1111/sms.12683.
De Filippo C, Cavalieri D, Di Paola M, Ramazzotti M, Poullet JB, Massart S, Collini S, Pieraccini G, Lionetti P. Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. Proceedings of the National Academy of Sciences 2010;107(33):14691-6. doi: 10.1073/pnas.1005963107.
De Filippo C, Di Paola M, Ramazzotti M, Albanese D, Pieraccini G, Banci E, Miglietta F, Cavalieri D, Lionetti P. Diet, Environments, and Gut Microbiota. A Preliminary Investigation in Children Living in Rural and Urban Burkina Faso and Italy. Frontiers in Microbiology 2017;8(1979). doi: 10.3389/fmicb.2017.01979.
Rothschild D, Weissbrod O, Barkan E, Kurilshikov A, Korem T, Zeevi D, Costea PI, Godneva A, Kalka IN, Bar N, et al. Environment dominates over host genetics in shaping human gut microbiota. Nature 2018;555(7695):210-5. doi: 10.1038/nature25973.
Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial [published correction appears in JAMA. 2018 Apr 3;319(13):1386] [published correction appears in JAMA. 2018 Apr 24;319(16):1728]. JAMA. 2018;319(7):667‐679. doi:10.1001/jama.2018.0245
Zeevi D, Korem T, Zmora N, Israeli D, Rothschild D, Weinberger A, Ben-Yacov O, Lador D, Avnit-Sagi T, Lotan-Pompan M. Personalized nutrition by prediction of glycemic responses. Cell 2015;163(5):1079-94.
Korem T, Zeevi D, Zmora N, Weissbrod O, Bar N, Lotan-Pompan M, Avnit-Sagi T, Kosower N, Malka G, Rein M, et al. Bread affects clinical parameters and induces gut microbiome-associated personal glycemic responses. Cell metabolism 2017;25(6):1243-53. doi: 10.1016/j.cmet.2017.05.002.
Clemente JC, Ursell LK, Parfrey LW, Knight R. The impact of the gut microbiota on human health: an integrative view. Cell 2012;148(6):1258-70.
Hjorth MF, Zohar Y, Hill JO, Astrup A. Personalized dietary management of overweight and obesity based on measures of insulin and glucose. Annual review of nutrition 2018;38:245-72. doi: 10.1146/annurev-nutr-082117-051606.
Katz, D., Bittman, M. and Katz, C., n.d. The Truth About Food. 2018.
Hemler EC, Hu FB. Plant-Based Diets for Cardiovascular Disease Prevention: All Plant Foods Are Not Created Equal. Current atherosclerosis reports 2019;21(5):18.
Hu FB. Plant-based foods and prevention of cardiovascular disease: an overview. The American Journal of Clinical Nutrition 2003;78(3 Suppl):544S-51S.
Bere E, Brug J. Towards health-promoting and environmentally friendly regional diets–a Nordic example. Public health nutrition 2009;12(1):91-6. doi: 10.1017/S1368980008001985.