The Atkins Diet is a popular weight loss plan based on eating fewer carbohydrates and more fatty foods - low-carbohydrate:high-fat (LCHF) diet.
Dr Robert Atkins, an American heart doctor (cardiologist), read about the way in which a diet low in carbohydrates can help the body to burn fat instead of glucose as fuel. He tried it out to solve his own weight problem. He then wrote a book, Dr Atkins' Diet Revolution, about his nutritional plan, which was published in 1972. The diet really took off in popularity after Dr Atkins' New Diet Revolution was published in 2002. The new book developed the ideas set out in the first book.
How does the Atkins Diet work?
Traditional weight loss plans focus on reducing energy-dense fats in the diet, and they recommend that one third of a meal should be composed of starchy foods such as pasta, bread or potatoes. Carbohydrates, whether simple sugars which are found in sweet foods, or complex starches, are digested to become glucose. This is the usual energy source for all the body's cells. When we eat carbohydrates, the body releases a body chemical (hormone) called insulin which processes the glucose.
However, if the body does not have carbohydrates, insulin levels remain low and this triggers a process called ketosis. In ketosis, the body uses fat reserves to provide energy. In the original Atkins Diet plan, carbohydrates were severely restricted in the initial diet phase and this led to rapid weight loss. More recent updates to the plan allow a small amount of carbohydrate in the diet and weight loss is generally more gradual. It also means that less extreme ketosis occurs.
There is an initial induction phase to the diet, lasting about two weeks. During this phase, protein foods such as meat and fish are eaten freely. Recommended recipes contain much more fat than most dieters are used to, including cheese and cream. During the second phase, the carbohydrate intake is gradually increased, and weight loss continues more gradually. When the target weight is reached, carbohydrate intake is gradually increased to find the balance point at which weight is comfortably maintained.
Does the Atkins Diet work?
Many people have found LCHF diets such as the Atkins Diet an effective way of weight loss and weight management. This may be because of the induction of ketosis, as described by Atkins. However, since most of our energy intake usually comes from carbohydrates, restricting them may simply have the effect of reducing overall energy intake. Also, high-protein foods increase the feeling of fullness after eating (satiety), so that may reduce hunger pangs.
Several studies comparing the outcomes of low-fat and low-carbohydrate diets concluded that both are effective for those who are able to stick to the diet plan. There seems to be no clear advantage of one over the other in terms of short- or long-term effectiveness. The health risks and benefits are similar.
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Is the Atkins Diet safe?
The mild dietary ketosis induced by eating a low-carbohydrate diet should not be confused with the dangerous condition of ketoacidosis. Ketoacidosis can be life-threatening in those with diabetes, who are not able to control the levels of the chemical (hormone) called insulin and glucose in their bodies. However, mild ketosis during the initial phase of the Atkins Diet can cause some symptoms such as:
- Feeling sick (nausea)
Some people have found that a low-carbohydrate diet can result in depression, although this may be offset by the effective weight loss.
Because the Atkins Diet advises eating habits different from those which are traditionally recommended, many health professionals have been hesitant to recommend it. Concerns have been raised about the way in which this diet might affect those who follow it. There has been a lot of publicity, both positive and negative. A lot of research has been carried out, and is ongoing. However, it is sometimes difficult to obtain a clear answer to some of the complex questions about diet.
There have been some concerns that a high meat intake might increase the body's levels of saturated fat. This might cause a higher risk of stroke or heart disease. The results of studies done to investigate this question have been inconclusive. Some risk factors are reduced while others are increased. One study recommended that eating protein and fat from foods other than red or processed meat would reduce the risk of developing diabetes on a low-carbohydrate diet.
There were concerns that high-fat low-carbohydrate diets would result in an increased risk of obesity, heart disease, stroke and diabetes; however, long-term studies suggest the reverse is true.
Other questions concern the low levels of fibre consumed in a low-carbohydrate diet. Fibre is necessary to keep our bowels moving healthily. A diet low in fibre may lead to an increased risk of developing bowel cancer. Fruits and vegetables are carbohydrate-containing foods which are restricted particularly in the initial phase of the Atkins Diet. There are concerns that people who stick to a low-carbohydrate diet for a long time may miss out on vitamins and other important nutrients in fruit and vegetables.
One study found that a diet high in protein and low in carbohydrate affected the balance of the 'friendly' bacteria in the gut. This could have an effect on the health of the colon (the lower part of the bowel, or 'large intestine').
Other concerns which have been raised include a possible increase in non-alcoholic fatty liver disease or kidney stones, especially in people who stick to the diet for a long time. One research paper showed that following a high-protein diet could further damage kidneys if they were already failing. There was, however, no risk to healthy kidneys.
Another criticism of the diet is that it can be quite expensive to follow. A meat-based diet costs more than one based on starchy foods and vegetables.
Are there other benefits to the Atkins Diet?
High-protein ketogenic diets are used in the management of some medical conditions. Ketogenic diets have been used to treat epilepsy since about 1920. However, today they are mainly used for children with difficult-to-control epilepsy. Recent studies have confirmed its effectiveness for this purpose, but questions have been raised about its long-term effects on cardiovascular health. The use of this diet in children with epilepsy should only be tried under guidance from a doctor.
A low-carbohydrate diet may also benefit those with disorders such as type 2 diabetes and polycystic ovary syndrome. In these conditions one of the problems is the way the body processes sugars and the chemical (hormone) called insulin. Often they find losing weight by following a traditional low-fat diet particularly difficult.
The Atkins Diet seems to be an effective way of losing weight for many people. However, eating a low-carbohydrate and high-protein diet has many different effects on different systems in the body. These are not fully understood and are still being investigated.
What other options are there to lose weight?
Other types of diet are available - for example:
There are other ways of changing your diet and altering your lifestyle to help you lose weight, such as increasing your physical activity.
You may find other leaflets in this series helpful, including:
Further reading and references
Obesity; NICE CKS, June 2015 (UK access only)
Johnston BC, Kanters S, Bandayrel K, et al; Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. JAMA. 2014 Sep 3312(9):923-33. doi: 10.1001/jama.2014.10397.
Harvie MN, Pegington M, Mattson MP, et al; The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomized trial in young overweight women. Int J Obes (Lond). 2011 May35(5):714-27. doi: 10.1038/ijo.2010.171. Epub 2010 Oct 5.
Noakes TD, Windt J; Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. Br J Sports Med. 2017 Jan51(2):133-139. doi: 10.1136/bjsports-2016-096491.
Guasch-Ferre M, Babio N, Martinez-Gonzalez MA, et al; Dietary fat intake and risk of cardiovascular disease and all-cause mortality in a population at high risk of cardiovascular disease. Am J Clin Nutr. 2015 Dec102(6):1563-73. doi: 10.3945/ajcn.115.116046. Epub 2015 Nov 11.
Hooper L, Abdelhamid A, Bunn D, et al; Effects of total fat intake on body weight. Cochrane Database Syst Rev. 2015 Aug 7(8):CD011834. doi: 10.1002/14651858.CD011834.
Martin K, Jackson CF, Levy RG, et al; Ketogenic diet and other dietary treatments for epilepsy. Cochrane Database Syst Rev. 2016 Feb 92:CD001903. doi: 10.1002/14651858.CD001903.pub3.
Gratz SW, Hazim S, Richardson AJ, et al; Dietary carbohydrate rather than protein intake drives colonic microbial fermentation during weight loss. Eur J Nutr. 2018 Feb 20. pii: 10.1007/s00394-018-1629-x. doi: 10.1007/s00394-018-1629-x.
Chang CK, Borer K, Lin PJ; Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance? J Hum Kinet. 2017 Mar 1256:81-92. doi: 10.1515/hukin-2017-0025. eCollection 2017 Feb.