In recent years, the ketogenic diet has been attracting a lot of attention for the management of numerous health conditions, as well as for weight loss. Some controversy still exists about its safety and efficacy, largely stemming from a lack of longitudinal and mechanistic studies, inconsistencies in diet composition in different cohorts, and disagreement in conclusions between research conducted on animal vs. human populations.
Also worth noting is that low-carbohydrate, low-GI, and Mediterranean diets led to significant improvements in blood lipids with up to a 4–10% increase in HDL (4% in the Mediterranean, 5% in low-GI, and 10% in low-carbohydrate diets), 1–4% reduction in LDL (1% in low-carbohydrate, 3% in low-GI, and 4% in Mediterranean diets), and 9% reduction in triglycerides. 
A small Feb. 20, 2017, study looked at the impact of a six-week ketogenic diet on physical fitness and body composition in 42 healthy adults. The study, published in the journal Nutrition & Metabolism, found a mildly negative impact on physical performance in terms of endurance capacity, peak power and faster exhaustion. Overall, researchers concluded, “Our findings lead us to assume that a [ketogenic diet] does not impact physical fitness in a clinically relevant manner that would impair activities of daily living and aerobic training.” The “significant” weight loss of about 4.4 pounds, on average, did not affect muscle mass or function.
To get the most benefit from the Keto diet, you should stay physically active. You might need to take it easier during the early ketosis period, especially if you feel fatigued or lightheaded. Walking, running, doing aerobics, weightlifting, training with kettlebells or whatever workout you prefer will boost your energy further. You can find books and online resources on how to adapt Keto meals or snacks for athletic training.
Gary D. Foster, Ph.D., Holly R. Wyatt, M.D., James O. Hill, Ph.D., Brian G. McGuckin, Ed.M., Carrie Brill, B.S., B. Selma Mohammed, M.D., Ph.D., Philippe O. Szapary, M.D., Daniel J. Rader, M.D., Joel S. Edman, D.Sc., and Samuel Klein, M.D., “A Randomized Trial of a Low-Carbohydrate Diet for Obesity — NEJM,” N Engl J Med 2003; 348:2082- 2090. http://www.nejm.org/doi/full/10.1056/NEJMoa022207.
Similar to our results, three studies noted that diabetes medications were reduced in some participants[6,8,9], although details were provided in only one study. We also discontinued diuretic medications during diet initiation because of concern for additional diuresis incurred by the diet. This concern was based on the theoretical effects of the diet , observed effects of the diet on body water by bioelectric impedance , and practical experience with the diet . Until we learn more about using low carbohydrate diets, medical monitoring for hypoglycemia, dehydration, and electrolyte abnormalities is imperative in patients taking diabetes or diuretic medications.
A survey of 1,580 low-carb consumers published in late 2017 by the Journal of Insulin Resistance45 found that while more than 11% of respondents reported using sleep-aids before beginning their low-carb diet, less than 5% reported using them after their diet. Moreover, nearly seven in 10 reported improved quality of sleep after dieting while only 3.4% said their sleep quality had worsened.
There isn't "a" Mediterranean diet. Greeks eat differently from Italians, who eat differently from the French and Spanish. But they share many of the same principles. Working with the Harvard School of Public Health, Oldways, a nonprofit food think tank in Boston, developed a consumer-friendly Mediterranean diet pyramid that offers guidelines on how to fill your plate – and maybe wineglass – the Mediterranean way.
People claiming huge benefits of these supplements – despite the lack of solid scientific support – may sometimes have a financial reason to believe in the supplements. Some of these products are sold under a multi-level marketing arrangement, where sales people are paid based on commission. For example, the company Prüvit sells drinkable ketones, called KETO//OS with a multi-level marketing structure.