Dieting (nutrition)

Dieting refers to a person’s deliberate attempts to tailor their food intake to a level consistent with the amount of food their body needs to fuel activity and maintain a healthy or otherwise ideal weight. Dieting is deliberate and planned, most often reflecting a person’s need to decrease, or in some cases increase, their total body weight. Other specialized diets are used to control the symptoms or reduce the risk of certain diseases, such as diabetes or metabolic syndrome. Nutritionists have long held that maintaining a balanced diet—that is, one that includes all the main macronutrients and micronutrients in appropriate proportions—is one of the best ways to ensure good health.

The main focus of dieting is achieving the proper balance between the calories a person eats and their body’s energy expenditure. If a person is seeking to lose weight, they need to create a caloric deficit by consuming fewer calories than their body uses over a period of time or by increasing their activity level to burn more calories. Fad diets often promote weight-loss strategies of restricting or avoiding the consumption of particular foods, such as carbohydrates, fats, or gluten, but calories are the main driver of weight management.

Brief History

The concept of a relationship between diet and health dates to antiquity; the word diet is derived from the Greek diaita, which means manner of living. By the Middle Ages, physicians believed that each type of food was associated with a particular humor and that a person’s diet could influence one’s overall health by bringing the four humors into balance. In the sixteenth century, diet books began to proscribe the consumption of particular foods, particularly sweets. The earliest known weight-loss programs date to the early eighteenth century. These diets proposed limiting the consumption of bread, butter, milk, and sugar. Excess weight was seen as a peril to health and as a moral failing, suggesting gluttony or a lack of control over the appetites. Doctors prescribed a variety of extreme "cures" for poor diets, including all-liquid diets (most often a mix of water and wines), all-fruit diets, smoking tobacco as a way to cleanse the body, and purging (vomiting) to maintain a healthy weight.

The Victorian period took a different perspective on obesity, as girth increasingly became a symbol of wealth. Men and women viewed being slightly overweight as a sign of a person’s elevated social position. Yet doctors continued to caution that food and health were related. By the early twentieth century, weight-loss programs and diet regimens were increasingly advertised and marketed to the public. Following World War II, people’s physical appearance became an increasingly central concern with the emergence of image technologies such as film and television, and diets became increasingly popular.

The volume of diet products and weight-loss services available on the market increased significantly during the early twenty-first century and included a wide spectrum of over-the-counter supplements. In 2014, the diet and weight-loss industries in the United States were valued at $64 billion, according to Marketdata Enterprise. By 2022, the research firm reported that the market had grown to approximately $76 billion. Trends during this period included diets centered on unprocessed foods and convenient meal preparation, but meal replacements (such as protein powders) were still positioned for growth. However, new medications like Ozempic and Wegovy, designed to treat Type 2 diabetes and often referred to as GLP-1 drugs, began to be used off-label for weight loss purposes. The meteoric rise of such drugs in the 2020s threatened the weight-loss industry, as many consumers no longer had a need for dieting.

Other trends impacting the weight-loss and diet industry around this time included the "anti-diet" movement, which also gained traction in the early 2020s. Mainly spread by social media influencers, including some dietitians who were compensated by the food industry for sharing those views, anti-diet messaging encouraged people to stop dieting altogether. By espousing messages that denounced "food shaming" and society's obsession with weight, and encouraging people to not worry about eating processed foods, anti-diet views resulted in essentially shifting the focus away from the food industry that manufactured ultra-processed foods. Critics of the movement warned that such messaging encouraged unhealthy behaviors in people with serious diseases like diabetes.

Overview

Diet services and products, fad diets, and myths surrounding weight loss and gain all contribute to a confusing morass of information regarding the effectiveness and safety of particular diets, especially in the long term. There are many different types of diets, including low-fat, low-carbohydrate, low-calorie or very-low-calorie, and detox diets. Low-fat diets involve reducing the percentage of fat in the diet, typically so that dietary fats account for approximately 20 percent of a person’s daily calorie intake. However, many low-fat processed food products contain high levels of added sugars, and there is limited evidence on the long-term effectiveness of low-fat diets in promoting weight loss or preventing heart disease. Low-carb diets, such as the widely popular Atkins, paleolithic (paleo), and ketogenic (keto) diets, reduce the intake of carbohydrates and emphasize protein and healthy fats. Low-carb diets and weight loss have been found to be helpful in managing the symptoms of certain health conditions, such as metabolic syndrome, diabetes, high blood pressure, and cardiovascular disease. However, the excessive restriction of carbohydrates in the diet can cause headache, weakness or fatigue, constipation or diarrhea, and vitamin or mineral deficiencies. As the population ages, eating for brain health, including eating more "superfoods" such as nutrient-dense whole foods like leafy green vegetables, berries, and nuts, is increasingly promoted to provide possible health benefits.

Low-calorie diets do not encourage restricting any particular food type but focus instead on reducing overall caloric intake to promote weight loss. However, certain foods, particularly those with complex carbohydrates, healthy fats, and high levels of fiber, help an individual feel fuller for longer periods of time than foods with simple carbohydrates and sugars. A number of factors, including age, gender, height, weight, and activity level, affect a person’s total daily energy expenditure, which estimates how many calories a person burns each day. The US Centers for Disease Control and Prevention (CDC) reports that gradual and steady weight loss is more likely to be sustainable over the long term and recommends creating a deficit of 500 to 1,000 calories per day for weight loss of about one to two pounds per week. Even modest weight loss of 5 to 10 percent of a person’s total body weight through calorie restriction provides measurable health benefits, such as reductions in blood pressure and improvements in cholesterol and glucose levels in the blood.

Although consensus can be difficult to reach given the sheer number of diet programs available, most nutritionists counsel balance—moderating food portions, eating a healthy variety of foods, eating at a slower and more concentrated pace, cutting back on added sodium, avoiding excessive alcohol intake, minimizing red meats and sugars, increasing intake of fruits and vegetables, checking one’s weight regularly, and maintaining an adequate level of physical exercise and sleep patterns. The CDC also emphasizes physical activity as well as weight loss to achieve meaningful health.

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