Either there are very few participants in the studies, they don’t have an even number of males vs. females, or they don’t last but a few months. One study only looked at 28 people; only 21 completed the study and 20 of these participants were men. On top of this, they were only followed for 16 weeks. Okay, so we see that 20 men can limit their carbohydrates severely for 4 months and lose weight which automatically makes their A1c come down. Great! So, the real question is, how long can these 20 men stay on this diet for the rest of their lives? How long would you like to go without eating any fresh fruit? I’m craving some now, so I’m taking a break to go grab a snack now!
The Mediterranean diet has long been recognized as one of the healthiest and most delicious ways to eat. The core concept behind this healthy diet is to eat like the people who live in the Mediterranean region—fill your plate with fresh fruits and vegetables, healthy fats, whole grains, legumes and fish and enjoy moderate amounts of red wine. This 7-day Mediterranean meal plan features these good-for-you foods and delicious flavors for a week of healthy of eating. Plus, at 1,200 calories you're on track to lose a healthy 1 to 2 pounds per week.
“I think the caution with a low-carbohydrate diet is the idea that it’s very restrictive,” Zeratsky says. “When you start getting into the very low carbohydrates, when you’re talking about 20 grams, which for some people would be a cup of [starchy] vegetables. … If there is someone who is interested in it, it’s very important they understand what a low carbohydrate diet means in a practical sense.”
Popularized by the documentary Forks Over Knives, the Ornish diet is a low-fat, plant-based diet plan based on whole grains, vegetables, fruits, and legumes. It's based on a lacto-ovo style of vegetarianism, allowing only egg whites and nonfat dairy products. It's packed with vitamins, fiber, and lots of filling plants to keep you satiated. Some studies have shown it can reverse heart disease and have beneficial effects on other chronic health conditions. (BTW, there is a difference between a vegan diet and a plant-based diet.)
That’s because the DASH Diet has been proven to work, says Reshmi Srinath, M.D., an assistant professor at the Icahn School of Medicine at Mount Sinai. One study found that people who followed the DASH Diet had lower blood pressure and LDL (bad) cholesterol levels than those who consumed a typical American diet or an American diet infused with extra fruits and veggies.
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. 
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.