Between 55 million and 75 million Americans are on a weight loss diet at any time. There are dozens of currently popular weight loss diets, and people may still be following one of the hundreds of diets from past years. They may follow a diet constantly, or be on and off it, or just follow the latest diet for a week or a month. They may even follow a combination of diets to suit their needs. Here are some major types of weight loss diets; note that some diets will overlap these categories and also that many of these diets are also used as healthy eating diets.
Types of weight loss diets
Low-calorie and ultra-low-calorie diets are based on the theory that you can lose weight if the number of calories you eat are less than the number of calories your body uses for metabolism. They are still the basis of diets recommended by government bodies, but are reducing in popularity. People on calorie-restriction diets typically restrict or avoid high-calorie foods such as fats and sugar.
Low-fat diets often go hand-in-hand with calorie-restriction diets. The theory is that “fat makes you fat” – partly because fats have higher calories for their weight than proteins and carbohydrates, and partly because fat itself is believed to have a negative impact on health. The concept of bad fat has changed over time – a number of decades ago all fat was believed to be bad. Then saturated fat was demonized and polyunsaturated fat believed to be the best for you. The reaction of food companies was to produce solid fats from polyunsaturated fats, which became hydrogenated or trans-fats. Later it was realized these were bad for you. Now many experts believe that high omega-6 ratios are bad for you and recommend reducing intake of omega-6 fats (such as vegetable oil, soy oil, corn oil, sunflower oil, and fats in meats from grain-fed animals) in comparison to omega-3 fats (such as olive oil and fats in wild fish). Fat-restriction diets typically recommend restricting or avoiding foods such as butter and high-fat animal meats.
Low-carb or ketogenic diets – these have existed for well over a hundred years, and most recently were popularized by Atkins and the South Beach Diet. They generally call for an induction phase where all foods containing carbohydrates are avoided, then further phases where “healthy” carbohydrates are reintroduced. Initially, foods such as sugars, grains and flour, starchy vegetables, and fruits are avoided. In later phases some foods including lower-sugar fruits and starchy vegetables and whole grains may be reintroduced. These diets have recently changed to become more in line with current thinking about healthy eating, by including leafy greens in all stages of the diet.
Glycemic-index (GI) diets – these distinguish between “good” and “bad” carbohydrates in terms of their effects on blood sugar levels. High GI food such as white bread, processed breakfast cereals, baked potatoes, and glucose are excluded from the diet. Medium GI foods such as whole wheat products, sweet potatoes, and sucrose are eaten sparingly, and low GI foods such as most fruits and vegetables, legumes, whole grains, nut, and fructose are acceptable.
Sugar elimination diets – cane sugar, and often other sugars as well, are excluded from these diets.
Carb cycling diets – these encourage cycles of high carb, low carb, and no carb days.
Natural and ancestral diets
Natural / no processed foods diets – these discourage eating processed food such as flour, sugar, artificial additives, and other foods that have been highly processed. The Mediterranean diet is one type. @@@
Paleolithic / primal / caveman / hunter-gatherer diets – these diets aim to take us back to eat like our ancestors tens of thousands of years ago before agriculture. In general, they avoid grains of all kinds, sugar, legumes, and dairy, and encourage consumption of pastured meats and wild fish rather than farmed.
Other types of diets
There are many other types of weight loss diet, including high fiber, blood type diets, cleansing and detoxing, blood or metabolic type, alkaline, food combining, volumetric, juicing, and more.