What it is: Low-carb diet that used to be hella popular
Drawbacks: "This high-protein plan is difficult to maintain for the long term. Your calorie intake is reduced drastically in the beginning phases of this plan. Nutritional concerns relate to the limitation of food containing carbohydrates. Many carbohydrate foods are drivers of important nutrients. Therefore, if you cut back or eliminate a nutrient like fiber, you may increase your risk for digestive or elimination troubles."
What it is: A diet that focuses mostly on plants and meat (no sugar, bread, fruit, milk...)
Drawbacks: "The nutritional concerns for this diet will depend on which foods (that contain carbohydrates) are eliminated or reduced. Carbohydrate-containing foods aren’t just bread, cereal, and grains, but also fruit, milk, yogurt, beans, and starchy vegetables. A low-carb diet can be deficient in calcium, vitamin D, vitamin C, or potassium, depending on which carbs you eliminate."