Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on calorie intake, different kinds of calorie-reduced diets, such as those emphasising particular macronutrients, have been shown to be no more effective than one another. As weight regain is common, diet success is best predicted by long-term adherence. Regardless, the outcome of a diet can vary widely depending on the individual.
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
Abdominal obesity, also known as central obesity and truncal obesity, is the human condition of an excessive concentration of visceral fat around the stomach and abdomen to such an extent that it is likely to harm its bearer's health. Abdominal obesity has been strongly linked to cardiovascular disease, Alzheimer's disease, and other metabolic and vascular diseases.
The Atkins diet is a low-carbohydrate fad diet devised by Robert Atkins in the 1970s, marketed with claims that carbohydrate restriction is crucial to weight loss and that the diet offered "a high calorie way to stay thin forever".
The glycemic (glycaemic) index is a number from 0 to 100 assigned to a food, with pure glucose arbitrarily given the value of 100, which represents the relative rise in the blood glucose level two hours after consuming that food. The GI of a specific food depends primarily on the quantity and type of carbohydrate it contains, but is also affected by the amount of entrapment of the carbohydrate molecules within the food, the fat and protein content of the food, the amount of organic acids in the food, and whether it is cooked and, if so, how it is cooked. GI tables, which list many types of foods and their GIs, are available. A food is considered to have a low GI if it is 55 or less; high GI if 70 or more; and mid-range GI if 56 to 69.
The Zone diet is a fad diet emphasizing low-carbohydrate consumption. It was created by Barry Sears, an American biochemist.
Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates are limited, and replaced with foods containing a higher percentage of fat and protein, as well as low carbohydrate foods.
The glycemic load (GL) of food is a number that estimates how much the food will raise a person's blood glucose level after it is eaten. One unit of glycemic load approximates the effect of eating one gram of glucose. Glycemic load accounts for how much carbohydrate is in the food and how much each gram of carbohydrate in the food raises blood glucose levels. Glycemic load is based on the glycemic index (GI), and is calculated by multiplying the weight of available carbohydrate in the food (in grams) by the food's glycemic index, and then dividing by 100.
A high-protein diet is a diet in which 20% or more of the total daily calories come from protein. Many high protein diets are high in saturated fat and restrict intake of carbohydrates.
Hyperinsulinemia is a condition in which there are excess levels of insulin circulating in the blood relative to the level of glucose. While it is often mistaken for diabetes or hyperglycaemia, hyperinsulinemia can result from a variety of metabolic diseases and conditions, as well as non-nutritive sugars in the diet. While hyperinsulinemia is often seen in people with early stage type 2 diabetes mellitus, it is not the cause of the condition and is only one symptom of the disease. Type 1 diabetes only occurs when pancreatic beta-cell function is impaired. Hyperinsulinemia can be seen in a variety of conditions including diabetes mellitus type 2, in neonates and in drug-induced hyperinsulinemia. It can also occur in congenital hyperinsulinism, including nesidioblastosis.
The Montignac diet is a high-protein low-carbohydrate fad diet that was popular in the 1990s, mainly in Europe. It was invented by Frenchman Michel Montignac (1944–2010), an international executive for the pharmaceutical industry, who, like his father, was overweight in his youth. His method is aimed at people wishing to lose weight efficiently and lastingly, reduce risks of heart failure, and prevent diabetes.
A very-low-calorie diet (VLCD), also known as semistarvation diet and crash diet, is a type of diet with very or extremely low daily food energy consumption. VLCDs are defined as a diet of 800 kilocalories (3,300 kJ) per day or less. Modern medically supervised VLCDs use total meal replacements, with regulated formulations in Europe and Canada which contain the recommended daily requirements for vitamins, minerals, trace elements, fatty acids, protein and electrolyte balance. Carbohydrates may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. Medically supervised VLCDs have specific therapeutic applications for rapid weight loss, such as in morbid obesity or before a bariatric surgery, using formulated, nutritionally complete liquid meals containing 800 kilocalories or less per day for a maximum of 12 weeks.
A diabetic diet is a diet that is used by people with diabetes mellitus or high blood sugar to minimize symptoms and dangerous complications of long-term elevations in blood sugar.
Gary Taubes is an American journalist, writer, and low-carbohydrate / high-fat (LCHF) diet advocate. His central claim is that carbohydrates, especially sugar and high-fructose corn syrup, overstimulate the secretion of insulin, causing the body to store fat in fat cells and the liver, and that it is primarily a high level of dietary carbohydrate consumption that accounts for obesity and other metabolic syndrome conditions. He is the author of Nobel Dreams (1987); Bad Science: The Short Life and Weird Times of Cold Fusion (1993); Good Calories, Bad Calories (2007), titled The Diet Delusion (2008) in the UK and Australia; Why We Get Fat: And What to Do About It (2010); The Case Against Sugar (2016); and The Case for Keto: Rethinking Weight Control and the Science and Practice of Low-Carb/High-Fat Eating (2020). Taubes's work often goes against accepted scientific, governmental, and popular tenets such as that obesity is caused by eating too much and exercising too little and that excessive consumption of fat, especially saturated fat in animal products, leads to cardiovascular disease.
The South Beach Diet is a popular fad diet developed by Arthur Agatston and promoted in his bestselling 2003 book. It emphasizes eating food with a low glycemic index, and categorizes carbohydrates and fats as "good" or "bad". Like other fad diets, it may have elements which are generally recognized as sensible, but it promises benefits not backed by supporting evidence or sound science.
Weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify the ideal body weights for different individuals.
Frank B. Hu is a Chinese American nutrition and diabetes researcher. He is Chair of the Department of Nutrition and the Fredrick J. Stare Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, and Professor of Medicine at the Harvard Medical School.
George A. Bray is an American obesity researcher. As of 2016, he is a University Professor emeritus and formerly the chief of the division of clinical obesity and metabolism at Louisiana State University's Pennington Biomedical Research Center in Baton Rouge. He is also a Boyd Professor emeritus at the Pennington Center, and a professor of medicine emeritus at the Louisiana State University Medical Center.
Preventive Nutrition is a branch of nutrition science with the goal of preventing, delaying, and/or reducing the impacts of disease and disease-related complications. It is concerned with a high level of personal well-being, disease prevention, and diagnosis of recurring health problems or symptoms of discomfort which are often precursors to health issues. The overweight and obese population numbers have increased over the last 40 years and numerous chronic diseases are associated with obesity. Preventive nutrition may assist in prolonging the onset of non-communicable diseases and may allow adults to experience more "healthy living years." There are various ways of educating the public about preventive nutrition. Information regarding preventive nutrition is often communicated through public health forums, government programs and policies, or nutritional education. For example, in the United States, preventive nutrition is taught to the public through the use of the food pyramid or MyPlate initiatives.
The carbohydrate-insulin model (CIM) posits that obesity is caused by excess consumption of carbohydrate, which then disrupts normal insulin metabolism leading to weight gain and weight-related illnesses. It is contrasted with the mainstream energy balance model (EBM), which holds that obesity is caused by an excess in calorie consumption compared to calorie expenditure. According to the carbohydrate–insulin model, low-carbohydrate diets would be the most effective in causing long-term weight loss. Notable proponents of the carbohydrate–insulin model include Gary Taubes and David Ludwig. The CIM has been tested in mice and humans. Although some experts consider that these studies falsified the CIM, proponents disagree. Available evidence does not support the existence of a long-term advantage in weight loss for low-carbohydrate diets.
