Christopher D. Gardner, PhD; Alexandre Kiazand, MD; Sofiya Alhassan, PhD; Soowon Kim, PhD; Randall S. Stafford, MD, PhD; Raymond R. Balise, PhD; Helena C. Kraemer, PhD; Abby C. King, PhD, “Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women,” JAMA. 2007;297(9):969-977. http://jama.jamanetwork.com/art icle.aspx?articleid=205916.
The Keto diet emphasizes weight loss through fat-burning. The goal is to quickly lose weight and ultimately feel fuller with fewer cravings, while boosting your mood, mental focus and energy. According to Keto proponents, by slashing the carbs you consume and instead filling up on fats, you safely enter a state of ketosis. That’s when the body breaks down both dietary and stored body fat into substances called ketones. Your fat-burning system now relies mainly on fat – instead of sugar – for energy. While similar in some ways to familiar low-carb diets, the Keto diet’s extreme carb restrictions – about 20 net carbs a day or less, depending on the version – and the deliberate shift into ketosis are what set this increasingly popular diet apart.
The DASH Diet Weight Loss Solution was chosen as one of top new diet plans of 2013 by The Today Show, while The DASH Diet Action Plan was named one of the top life-changing health books, by Huffington Post readers. See more recent news stories about the DASH diet. Meet the author and learn more about the weight loss plan by watching our Dr. Oz episode, the PBS show, or join one of our free support groups for weight loss or for the mostly vegetarian plan, or our new group for the Med-DASH plan on Facebook!
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.
Carbohydrate Restriction. To help people with diabetes manage their blood sugar levels, doctors will typically prescribe a diet that mostly consists of low glycemic index foods.  However, according to the research, restricting overall carb intake to the point of following a keto diet may be the best way to improve the many biomarkers relevant to diabetes.  In fact, this dietary strategy has been proven to be helpful for the management of type 2 diabetes and type 1 diabetes.
Cyclical keto diet: The Bulletproof Diet falls into this category. You eat high fat, low carb (less than 50 grams of net carbs a day) five to six days of the week. On day seven, you up your carb intake to roughly 150 grams, during what’s called a carb refeed day. Carb cycling this way helps you avoid the negative effects some people experience when they restrict carbs long term, like thyroid issues, fatigue and dry eyes. Learn more here about how carb cycling works.
Recently, four studies have re-examined the effect of carbohydrate restriction on type 2 diabetes. One outpatient study enrolled 54 participants with type 2 diabetes (out of 132 total participants) and found that hemoglobin A1c improved to a greater degree over one year with a low-carbohydrate diet compared with a low-fat, calorie-restricted diet [5,6]. Another study enrolled 8 men with type 2 diabetes in a 5-week crossover outpatient feeding study that tested similar diets . The participants had greater improvement in glycohemoglobin while on the low-carbohydrate diet than when on a eucaloric low-fat diet. The third study was an inpatient feeding study in 10 participants with type 2 diabetes . After only 14 days, hemoglobin A1c improved from 7.3% to 6.8%. In the fourth study, 16 participants with type 2 diabetes who followed a 20% carbohydrate diet had improvement of hemoglobin A1c from 8.0% to 6.6% over 24 weeks . Only these latter three studies targeted glycemic control as a goal, and two of these were intensely-monitored efficacy studies in which all food was provided to participants for the duration of the study [7,8]. Three of the studies [6,8,9] mentioned that diabetic medications were adjusted but only one of them provided detailed information regarding these adjustments . This information is critical for patients on medication for diabetes who initiate a low-carbohydrate diet because of the potential for adverse effects resulting from hypoglycemia.
Net carbs is simply total carbs minus fiber and non-digestible sugar alcohols, like erythritol. (This doesn’t apply to high glycemic sugar alcohols, like maltitol.) We don’t have to count fiber and certain sugar alcohols in net carbs, because they either don’t get broken down by our bodies, are not absorbed, or are absorbed but not metabolized. (Read more about sugar alcohols here.)
There’s a large spectrum of where people can fall on a vegetarian diet: For example, vegans consume no animal products, whereas ovo-lacto vegetarians eat both dairy and eggs. The eating style may help with weight loss, suggests a review published in August 2017 in Nutrients, but some vegans and vegetarians may become deficient in specific nutrients, such as calcium, iron, zinc, and vitamin B12, according to an article published in December 2017 in Nutrition, Metabolism and Cardiovascular Diseases. (23,24)
The DASH Diet, which stands for dietary approaches to stop hypertension, is promoted by the National Heart, Lung, and Blood Institute to do exactly that: stop (or prevent) hypertension, aka high blood pressure. It emphasizes the foods you've always been told to eat (fruits, veggies, whole grains, lean protein and low-fat dairy), which are high in blood pressure-deflating nutrients like potassium, calcium, protein and fiber. DASH also discourages foods that are high in saturated fat, such as fatty meats, full-fat dairy foods and tropical oils, as well as sugar-sweetened beverages and sweets. Following DASH also means capping sodium at 2,300 milligrams a day, which followers will eventually lower to about 1,500 milligrams. DASH Diet is balanced and can be followed long term, which is a key reason nutrition experts rank it as U.S. News’ Best Overall Diet, tied with the Mediterranean Diet.
Now, about that whole low-fat and low-sugar thing. It can be tricky come dessert time, but Gorin has a hack for surviving that as well: "One way to feel like you’re getting the dessert that you crave while still following the diet is to eat a fruit-based 'nice cream,' like my chocolate-banana recipe. By combining frozen bananas and unsweetened cocoa powder, you'll wind up with a treat that resembles the texture of ice cream yet contains no added sugar and also counts toward your daily fruit servings."
The first meta-analysis worth noting collected the data from 10 randomized trials comprising 1376 participants in total.  After analyzing the research, a key relationship emerged between dietary carbs and blood sugar levels. In short, the researchers described their finding thus: “the greater the carbohydrate restriction, the greater glucose lowering…” 
“Intermittent fasting can be really challenging if you have an ever-changing schedule,” adds Hultin. “If you're traveling and crossing time zones, it could be very difficult to follow. It might be best for people with more stability in their lives.” Intermittent fasting isn’t safe for people with type 2 diabetes, children, pregnant or lactating women, or anyone with a history of an eating disorder.
Sleep enough – for most people at least seven hours per night on average – and keep stress under control. Sleep deprivation and stress hormones raise blood sugar levels, slowing ketosis and weight loss a bit. Plus they might make it harder to stick to a keto diet, and resist temptations. So while handling sleep and stress will not get you into ketosis on it’s own, it’s still worth thinking about.