Even though theoretically anyone can benefit from a healthy diet, it’s recommended that you consult with your doctor before beginning a new diet plan. Also, there are people for whom certain plans may not be ideal, including people with diabetes, pregnant women, people allergic to certain foods, people with hypertension, and people with a history of eating disorders.
Based on the concept of caloric density, which states that some foods have few calories in proportion to their size (say, a lettuce), while others have lots of calories packed in small portions (a regular chocolate chip cookie comes to mind), Volumetrics divides foods into 4 categories based on their calorie/volume ratio, and is perfect for people looking to binge on some foods while still shedding pounds. However, as with the calorie counting approach, Volumetrics does not take into account the quality of the calories, prioritizing quantity instead. The app Noom and Weight Watchers (both reviewed above) share similarities with this diet theory.
Right now, this is the trendiest of all diet theories. It prioritizes the consumption of foods high in protein and fat while limiting the number of carbs per day to less than 20%. This means abstaining from grains, starchy vegetables, and fruits, and filling up on protein and fat. The most famous of all low-carb plans is the Keto Diet, an approach based on the metabolic process of ketosis, which happens when you restrict your carb intake to less than 0.7 grams per day and your body starts using fat, and not carbs, as its main fuel.
According to its fervent proponents, humans were not made to be eating constantly; rather, we were designed to eat for short periods of time followed by hours (and sometimes days) of fasting. Much like vegetarianism, intermittent fasting is practiced for two main reasons: health and religion/spirituality. There are no food or caloric restrictions, but rather a restriction on WHEN to eat. The most popular methods include the 16/8 (8 hours of eating followed by 16 hours of fasting), the “Eat-Stop-Eat” method (two 24-hour fasts per week on non-consecutive days); and the 5/2 method (only 500 calories for 2 non-consecutive days, and 5 days of normal eating per week). While it's generally considered a healthy approach to eating when done moderately, some studies suggest extreme fasting may lead to hair loss and anxiety.
If you like eating meat and want to lose weight, you might be tempted to try this recent extreme diet fad that proponents have made some pretty outrageous claims about. One: that eating nothing but meat can cure you of autoimmune diseases. The problem is that there’s no good research to support that notion, or any other health claim, for that matter. Indeed, omitting foods known to be good for you — fruits and veggies among them — can lead to a bunch of unwanted side effects, including constipation and potentially dangerous nutrient deficiencies. Still, since you’re cutting out so many food groups, there’s a decent chance you’ll lose weight, experts say. Regardless of any possible benefits you might see, this restrictive approach is definitely one you’ll want to ask your doc about before you even consider diving in.