The Atkins diet is a low-carbohydrate eating plan that became widely known for restricting carbohydrates while emphasizing foods such as meat, fish, eggs, vegetables, nuts and fats.
Created by US physician Robert Atkins, the diet gained popularity as an alternative to low-fat and calorie-restricted diets. The modern Atkins programme uses several phases, beginning with a very low carbohydrate intake and gradually adding more carbohydrates as a person approaches their weight-maintenance level.
The diet is based on the idea that reducing carbohydrate intake changes the body’s main source of energy. In the early phase of the classic Atkins plan, carbohydrate intake is limited to about 20 grams of net carbohydrates a day, with carbohydrates mainly coming from non-starchy vegetables. Net carbohydrates are calculated by subtracting fibre from total carbohydrates.
As carbohydrate intake falls, the body has less glucose available from food and begins relying more heavily on stored fat and other fuel sources. Very low-carbohydrate diets can also produce ketosis, a metabolic state in which the body produces ketones from fat for energy.
Does the Atkins diet help with weight loss?
Research suggests that reducing carbohydrate intake can help adults with overweight or obesity lose weight, particularly during the first several months.
A 2023 systematic review and dose-response analysis of 110 randomised controlled trials found that greater carbohydrate restriction was associated with greater reductions in body weight at six and 12 months. The researchers also found that the effect was less consistent beyond 12 months.
Other evidence suggests that the difference between low-carbohydrate and other weight-loss diets becomes smaller over time. A Cochrane review of randomised trials found little to no difference in weight loss between low-carbohydrate and balanced-carbohydrate diets over periods ranging from several months to two years.
This means the Atkins diet can be an effective approach for some people, but the evidence does not establish it as uniquely effective compared with other structured eating patterns.
What foods does Atkins emphasise?
The foods included in Atkins vary according to the phase of the programme.
The initial phase emphasises protein-rich foods such as poultry, fish, seafood, eggs and meat, together with non-starchy vegetables and sources of fat. Later phases progressively introduce foods such as nuts, seeds, berries, legumes, additional fruits, starchy vegetables and whole grains.
The modern programme therefore does not permanently eliminate all carbohydrates. Instead, carbohydrate intake is increased as a person moves through the phases and determines the amount that can be consumed while maintaining their goals.
Is a low-carbohydrate diet healthy?
The answer depends partly on which foods replace the carbohydrates.
Low-carbohydrate diets can improve some metabolic measures in certain people. Research in adults with type 2 diabetes has found that reducing carbohydrate intake can improve blood sugar control, particularly in the short term.
But cutting carbohydrates does not automatically make a diet healthier. Nutrition quality still matters. The American Diabetes Association recommends emphasizing non-starchy vegetables, whole fruits, legumes, whole grains, nuts and seeds, while limiting added sugars, refined grains and highly processed foods.
The type of fat consumed can also matter. A previous meta-analysis found that low-carbohydrate diets produced somewhat greater weight loss and improvements in triglycerides and HDL cholesterol than low-fat diets over six to 12 months, but LDL cholesterol and total cholesterol were more favourable with low-fat diets.
For that reason, replacing carbohydrates mainly with highly processed or saturated-fat-rich foods should not automatically be considered a healthy choice.
What about the “keto flu”?
People who make a substantial and sudden reduction in carbohydrate intake can experience short-term symptoms such as fatigue or feeling unwell during the transition. Atkins itself acknowledges that some people experience temporary symptoms when beginning a very low-carbohydrate approach.
The term “keto flu” is commonly used for these symptoms, although it is not the name of a specific medical disease.
Very-low-carbohydrate diets may also require particular care for people with certain medical conditions. The American Diabetes Association has noted concerns around very-low-carbohydrate eating patterns in groups including people with chronic kidney disease and pregnant women, while people taking glucose-lowering medication may need medical supervision because carbohydrate restriction can affect blood glucose levels and medication requirements.
The bottom line
Atkins is a structured low-carbohydrate eating pattern rather than a diet that eliminates carbohydrates altogether. Its first phase is particularly restrictive, while later phases progressively reintroduce carbohydrate-containing foods.
Evidence supports low-carbohydrate diets as one possible approach to weight management and, for some people with type 2 diabetes, blood sugar control. But research does not show that carbohydrate restriction is consistently superior to other balanced approaches over the long term.
Anyone considering a very low-carbohydrate diet, particularly someone who is pregnant, has a medical condition or takes medication that affects blood sugar, should discuss the approach with a qualified health professional before making major dietary changes.
