Detox diets are dietary plans that claim to have detoxifying effects. The general philosophy suggests that most food is contaminated by various ingredients deemed unnecessary for human life, such as flavor enhancers, food colorings, and artificial preservatives. Scientists, dietitians, and doctors, while generally judging ‘detox diets’ harmless (unless nutritional deficiency results), often dispute the value and need of ‘detox diets’ due to lack of supporting factual evidence or coherent rationale. Detox diets can involve consuming extremely limited foods (only water or juice, a form of fasting), or eliminating certain foods from the diet (such as fats). Proponents claim that this will cause the body to burn accumulated stored fats, releasing fat-stored “toxins” into the blood, which can then be eliminated through the blood, skin, urine, feces and breath. Proponents claim things like an altered body odor support the notion that detox diets are working; this claim has been criticized for misinterpreting the body undergoing ketosis. Though a brief fast of a single day is unlikely to cause harm, prolonged fasting can be fatal.

Body cleansing and detoxification have been referred to as an elaborate hoax used by con artists to cure nonexistent illnesses. Most doctors contend that the ‘toxins’ in question do not even exist. In response, alternative medicine proponents frequently cite heavy metals or pesticides as the source of toxification; however, no evidence exists that detoxification approaches have a measurable effect on these or any other chemical levels. Medical experts state that body cleansing is unnecessary as the human body is naturally capable of maintaining itself, with several organs dedicated to cleansing the blood and gut. Professor Alan Boobis OBE, Toxicologist, Division of Medicine, Imperial College London states that “The body’s own detoxification systems are remarkably sophisticated and versatile. They have to be, as the natural environment that we evolved in is hostile. It is remarkable that people are prepared to risk seriously disrupting these systems with unproven ‘detox’ diets, which could well do more harm than good.”

The apparently satisfied testimonial and anecdotal accounts by customers can be explained by either disguised employees creating false anecdotes, or actual customers who are experiencing the placebo effect after trying the products, natural recovery from an actual illness that would have occurred without the use of the product, psychological improvements on illnesses that are psychosomatic or the result of neurosis, and the fact that a large number of dissatisfied customers have not posted equally applicable anecdotes about their poorer experiences.

People from the islands of Ryūkyū (of which Okinawa is the largest) have a life expectancy among the highest in the world, although their life expectancy rank among Japanese prefectures has plummeted in recent years. Their unusual longevity has been attributed in part to the traditional local diet, but also to genetic inheritance, lifestyle, and environmental factors.

Generally, the traditional diet of the islanders was 20% lower in calories than the Japanese average and contained 300% of the green/yellow vegetables (particularly heavy on sweet potatoes). The Okinawan diet is low in fat and has only 25% of the sugar and 75% of the grains of the average Japanese dietary intake. The traditional diet also includes a relatively small amount of fish (less than half a serving per day) and somewhat more in the way of soy and other legumes (6% of total caloric intake). With exception of pork, almost no meat is consumed; virtually no eggs or dairy products are consumed either. Okinawans include pork in their diets. However, the fat content of the pork is eliminated; prior to the preparation of the pork, the fat is boiled off.

An Okinawan reaching 110 years of age has typically had a diet consistently averaging no more than one calorie per gram of food and has a BMI of 20.4 (also note that when values – such as caloric density – vary from 1x to 10x, the average is not relevant)

Commercial weight loss diet

The diet consists of a relatively low intake of calories and contains similar foods to the traditional Okinawan diet. The principal focus of the diet consists of knowing how many calories per gram each food item contains.

The proponents of this diet divide food into 4 categories based on caloric density. The “featherweight” foods, less than or equal to 0.8 calories per gram which one can eat freely without major concern, the “lightweight” foods with a caloric density from 0.8 to 1.5 calories per gram which one should eat in moderation, the “middleweight” foods with a caloric density from 1.5 to 3.0 calories per gram which one should eat only while carefully monitoring portion size and the “heavyweight” foods from 3 to 9 calories per gram which one should eat only sparingly.

Calorie restriction, or caloric restriction (CR), is a dietary regimen that restricts calorie intake, where the baseline for the restriction varies, usually being the previous, unrestricted, intake of the subjects. Calorie restriction without malnutrition has been shown to improve age-related health and to slow the aging process in a wide range of animals and some fungi. CR is one of the few dietary interventions that have been documented to increase both the median and maximum lifespan in a variety of species, among them yeast, fish, rodents and dogs. There are currently ongoing studies to investigate whether CR works in nonhuman primates, and its effects on human health and metabolic parameters associated with CR in other species. The results so far are positive, but the studies are not yet complete, due to the long lifespan of the species.

Calorie restriction is a feature of several dietary regimens, including the Okinawa diet and the CRON-diet.

Although most studies conducted showed that these diets can improve longevity and health in the long term, the effects of calorie restriction on humans is still controversial. Some studies on humans revealed a number of benefits of calorie restriction but also major side effects such as loss of muscle mass, muscle strength and loss of bone. In the middle aged or elderly low body weight is associated with premature mortality from cardiovascular disease and cancers. Confounds to these studies exist but higher mortality rates make the view that human CR leads to increases in lifespan as robust as CR leads to in rodents questionable nonetheless. An expert on aging has voiced concern over his CR practicing colleague Mark Mattson saying “This guy has no reserves.”

The health concerns in the case of calorie restriction begin when an individual cuts off too many calories. Researchers have reported that “excessive calorie restriction causes malnutrition and can lead to anemia, muscle wasting, weakness, dizziness, lethargy, fatigue, nausea, diarrhea, constipation, gallstones, irritability and depression”. Although calorie restriction may have potential benefits for individuals, the majority of nutritionists agree that a diet that does not comprise enough calories for the individual’s body may lead to serious health problems.

Many specialists believe that calorie restriction can make individuals feel hungry all the time and this may lead to them getting obsessed with food which can easily become the cause of various eating disorders. Most commonly, individuals who are trying to lose weight quickly with the help of calorie restriction diets are at risk of developing anorexia nervosa, a type of eating disorder.

The effect of these diets on people who want to lose weight is controversial. Although calorie restriction may provide quick weight loss, several studies have shown that the body adjusts to the new diet in more or less half a year. Researchers argue that people who have little body fat should not use this method of losing weight but rather should exercise more because calorie restriction in this case can be harmful. The reason for this is that after the body’s fat reserves have been burned for energy, the proteins within muscle tissue will be consumed. In severe cases where individuals do not acknowledge the dangers they are exposing themselves to, they may suffer serious loss of the muscle mass.

Several studies conducted in this sense revealed that dieters who restricted calories for 12 months had lower muscle mass and a reduced capacity to perform exercise compared with those who lost similar amounts of weight from exercise alone. Another study concluded that individuals who lost weight with the help of the calorie restriction diets are more prone to develop a loss of bone at the level of hip and spine, the area most at risk for bone fractures. Some specialists however claim that minor mineral losses can be prevented with supplements of vitamin D and calcium.

It has also been noted that people who are willing to lose weight by following such diets put themselves at risk of developing cold sensitivity, menstrual irregularities and even infertility and hormonal changes. Moreover, recent studies attack the earlier studies that found that calorie restriction may improve memory and attention. A study published in 2007 in Rejuvenation Research magazine shows that there is no significant link between this diet and memory or attention problems. Excessive calorie restriction may lead to swelling in the individual’s legs and feet.

A series of pie charts depicting the calorific contributions from carbohydrate, protein and fat in four diets: the typical American diet; the Atkins diet during the induction phase; the classic ketogenic diet in a 4:1 ratio of fat to combined protein and carbohydrate (by weight); and the MCT oil ketogenic diet.

Low-carbohydrate diets or low-carb diets are dietary programs that restrict carbohydrate consumption usually for weight control or for the treatment of obesity. Foods high in digestible carbohydrates (e.g. bread, pasta) are limited or replaced with foods containing a higher percentage of proteins and fats (e.g., meat, poultry, fish, shellfish, eggs, cheese, nuts, seeds, peanuts, and soy products) and other foods low in carbohydrates (e.g., most salad vegetables) although other vegetables and fruits (especially berries) are often allowed. The amount of carbohydrate allowed varies with different low-carbohydrate diets.

Such diets are sometimes ketogenic (i.e. they restrict carbohydrate intake sufficiently to cause ketosis) for example, the induction phase of the Atkins diet. Some sources, though, consider less restrictive variants to be low-carbohydrate as well.

Apart from obesity, low-carbohydrate diets are often used as treatments for some other conditions, most notably diabetes and epilepsy, but also for chronic fatigue syndrome (see ketosis) and polycystic ovarian syndrome.

However, in recent years the exact health benefits of a low-fat diet have been debated. A 2006 study published by the Journal of the American Medical Association argued that a low-fat diet did not reduce the incidence of breast cancer. However, this study was criticized by several epidemiologists for its lack of validity (see “Criticisms” in the Women’s Health Initiative article). Recently, the Nurses’ Health Study from the Harvard School of Public Health reported from a Dietary Approaches to Stop Hypertension (DASH), and found that a diet “with high intake of fruits, vegetables, and whole grains, moderate intake of legumes, nuts, and low-fat dairy products, and low intake of red and processed meats and sodium, was significantly associated with lower risk of coronary heart disease and stroke in women.” A 2002 Cochrane Review found low-fat diets to be no more effective than other weight loss diets in achieving lasting weight loss.

Diets to promote weight loss are generally divided into four categories: low-fat, low-carbohydrate, low-calorie, and very low calorie. A meta-analysis of six randomized controlled trials found no difference between the main diet types (low calorie, low carbohydrate, and low fat), with a 2–4 kilogram weight loss in all studies. At two years, all calorie-reduced diet types cause equal weight loss irrespective of the macronutrients emphasized.

The first popular diet was “Banting”, named after William Banting. In his 1863 pamphlet, Letter on Corpulence, Addressed to the Public, he outlined the details of a particular low-carbohydrate, low-calorie diet that had led to his own dramatic weight loss.