The Optimal Diet for Weight Loss… Which fad diet does it best?
There are so many diets these days that people SWEAR by. They will tell you that they went keto and lost 10 pounds in two weeks. Is this really a reduction in body weight? Does data really support any of these diets for sustained weight loss? Let’s looks at the research. Other popular diets right now are paleo, vegan, vegetarian, Mediterranean and intermittent fasting.
Keto
A ketogenic diet is when one consumes a high amount of fats, a moderate amount of protein and a very low amount of carbohydrates. Typically these fats will consist of 55-65% of their caloric intake for the day. 30-35% of calories will come from protein and only 5-10% of calories will come from carbohydrates (Masood, Annamaraju, & Uppaluri, 2023). The ranges for fats and carbohydrates are much different than what the Academy of Nutrition and Dietetics recommends. The recommended calories from fat are between 15-25% of totally calories and 55-70% for carbohydrates in adults (Lee et al., 2015). Low carb diets have been utilized in studies to determine their effectiveness for weight loss. People who followed this sort of diet successfully loss weight and it promoted glycemic control in those who had diabetes (Brouns, 2018). However, no long term risks and rewards were studied. While weight loss was achieved, most participants were unable to sustain this diet longer than 6 months and determined that it is not a diet that diabetic patients should continue long term. Additionally, while they were on this diet participants also reported gastrointestinal distress, and researchers predict that this type of diet could create cardiovascular complications down the road. The ketogenic diets are so high in overall fat as well as saturated fat which is linked with high cholesterol, stroke and heart disease.
Paleo
The Paleolithic diet, also known as the paleo diet, is one that mimics what cavemen used to eat. The principles of the diet are to obtain from processed foods, dairy, grains, sugar, legumes, oils, salt, alcohol and coffee and to choose foods such as fruits, vegetables, nuts, roots and meats. A few of these principles sound great, especially cutting out processed foods. However, cutting out large food groups such as grains and legumes can make it difficult for a person to sustain. When different diets were assessed in conjunction with high intensity interval training, those following a paleo diet were about to lose an average of 1.8 kilograms over a 12 month period. They were also one of the best diets in terms of adherence. The participants on a paleo diet did not see any improvement in their blood pressure or glycate hemoglobin, which indicates a person’s average blood glucose levels over 2-3 months (Jospe et al., 2020). Additional studies claim that paleo diet claims are exaggerated and likely do not improve metabolic function. Additionally, paleolithic diets are low in calcium and may put a person at risk for osteoporosis development in the future (Pitt, 2016).
Intermittent Fasting
Intermittent fasting (IF) is less of a diet and more based on time restricted eating. The basis of IF is to eat only within a certain time window, and not at all before or after this window. Typically one would have an 8 hour window to eat what they want, and for 16 hours they fast and cannot have anything other than water. Others will do a 12 hour eating window with a 12 hour fast, or 10 hour eating window with a 14 hour fast. Some people will drink coffee or other low calorie drinks during the fasting period. However, anything that triggers the gut breaks the fast. Participants who partook in IF lost 0.8-13% of their bodyweight during a 26 week long study and experienced little to no side effects. Glycemic control was also improved and determined that this can be a good tool for treating obesity (Welton et al., 2020). It is also been found that a 16 hour fast is the most effective for weight loss, however this may just be due to the lower intake of calories because there is a shorter eating window (Templeman, Gonzalez, Thompson, & Betts, 2020). In a study that was discussed previously, when IF was paired with high intensity interval training, participants lost an average of 0.4 kilograms over a 12 month period, which was much lower than other groups such as paleo or Mediterranean diets. Improvements in blood pressure were also observed for those who were fasting but it was difficult to adhere to the diet (Jospe et al., 2020).
Mediterranean Diet
Mediterranean diets are quite common in Europe and they are making their way to the US. This diet places a heavy emphasis on eating vegetables, fruits, and whole grains and their main source of fat comes from extra virgin olive oil. In a weight loss study participants on a Mediterranean diet lost 2.8 kilograms over a 12 month period. Along with IF, Mediterranean diets led to improvements in blood pressure. Additionally it was one of the diets that was most likely to be adhered to (Jospe et al., 2020). Another discovered that this diet was able to improve glycemic control, and still saw that it was difficult to adhere to (Chester, Babu, Greene, & Geetha, 2019)
Vegan and Vegetarian
Finally, we have vegan and vegetarian diets. Vegetarian diets typically are a diet that abstains from meat and fish. A vegan diet is more restrictive. Vegans do not eat anything that comes from an animal or animal derivative. Things that are avoided are meat, dairy, eggs, honey, gelatin, and more. Both of these diets have been shown to promote weight loss significantly more than non-vegetarian and vegan diets (Huang, Huang, Hu, & Chavarro, 2016). Low carbohydrate vegan diets have also been proven to health diabetic patients with weight loss and improved their glycemic control and blood pressure (Jenkins et al., 2022). This same version of a vegan diet also significantly changed the gut microbiota and influenced positive outcomes in terms of weight, body composition and insulin sensitivity in overweight adults (Kahleova et al., 2020). Vegan diets can also improve glycemic control by may be difficult to maintain in the long term (Chester et al., 2019).
Overview
Recent diets have been emerging with various claims about weight loss and improved biomarkers but which of these claims are actually supported by research? All diets appear to promote weight loss but this is likely due to their restrictive standards, leading to an overall caloric deficit. All diets, except paleo, appear to improve glycemic control. Intermittent fasting, Mediterranean and vegan/vegetarian diets all appeared to improve blood pressure. Finally, vegan/vegetarian diets also improved insulin sensitivity. While all of these diets provided various benefits, all proved to be difficult to adhere to. If you are someone who is looking to lose weight, the best diet for you is going to be one that you are able to maintain. Do not chose a keto diet if you know that you won’t be able to sustain it, and the same goes with all of these other diets. Start off with small ways to improve your diet such as adding in more fruits and vegetables and then slowly move into removing things from your diet such as processed foods. High intensity interval training is also be a great tool to combine with dietary changes. Which diet are you sold on?
References
Brouns, F. (2018). Overweight and diabetes prevention: is a low-carbohydrate-high-fat diet recommendable? Eur J Nutr, 57(4), 1301-1312. doi:10.1007/s00394-018-1636-y
Chester, B., Babu, J. R., Greene, M. W., & Geetha, T. (2019). The effects of popular diets on type 2 diabetes management. Diabetes Metab Res Rev, 35(8), e3188. doi:10.1002/dmrr.3188
Huang, R. Y., Huang, C. C., Hu, F. B., & Chavarro, J. E. (2016). Vegetarian Diets and Weight Reduction: a Meta-Analysis of Randomized Controlled Trials. J Gen Intern Med, 31(1), 109-116. doi:10.1007/s11606-015-3390-7
Jenkins, D. J. A., Jones, P. J. H., Abdullah, M. M. H., Lamarche, B., Faulkner, D., Patel, D., . . . Josse, R. G. (2022). Low-carbohydrate vegan diets in diabetes for weight loss and sustainability: a randomized controlled trial. Am J Clin Nutr. doi:10.1093/ajcn/nqac203
Jospe, M. R., Roy, M., Brown, R. C., Haszard, J. J., Meredith-Jones, K., Fangupo, L. J., . . . Taylor, R. W. (2020). Intermittent fasting, Paleolithic, or Mediterranean diets in the real world: exploratory secondary analyses of a weight-loss trial that included choice of diet and exercise. Am J Clin Nutr, 111(3), 503-514. doi:10.1093/ajcn/nqz330
Kahleova, H., Rembert, E., Alwarith, J., Yonas, W. N., Tura, A., Holubkov, R., . . . Barnard, N. D. (2020). Effects of a Low-Fat Vegan Diet on Gut Microbiota in Overweight Individuals and Relationships with Body Weight, Body Composition, and Insulin Sensitivity. A Randomized Clinical Trial. Nutrients, 12(10). doi:10.3390/nu12102917
Lee, E., Choi, J., Ahn, A., Oh, E., Kweon, H., & Cho, D. (2015). Acceptable macronutrient distribution ranges and hypertension. Clin Exp Hypertens, 37(6), 463-467. doi:10.3109/10641963.2015.1013116
Masood, W., Annamaraju, P., & Uppaluri, K. R. (2023). Ketogenic Diet. In StatPearls. Treasure Island (FL).
Pitt, C. E. (2016). Cutting through the Paleo hype: The evidence for the Palaeolithic diet. Aust Fam Physician, 45(1), 35-38. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27051985
Templeman, I., Gonzalez, J. T., Thompson, D., & Betts, J. A. (2020). The role of intermittent fasting and meal timing in weight management and metabolic health. Proc Nutr Soc, 79(1), 76-87. doi:10.1017/S0029665119000636
Welton, S., Minty, R., O'Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermittent fasting and weight loss: Systematic review. Can Fam Physician, 66(2), 117-125. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/32060194