Atkins diet guide: Benefits, risks and expert opinion

Atkins diet
The Atkins diet emphasises meat and fats over carbohydrates - Getty

Of all the fad diets, the Atkins diet is arguably the best known and has stood the test of time. Experts concede that it can be an effective weight loss plan, but it remains controversial, not least least because there are doubts over how healthy it is as a long-term eating pattern.

In essence, Atkins is a low-carbohydrate diet, the type of which is often endorsed by obesity and diabetes specialists. Indeed, some trials show that the low-carb approach helps people lose weight at least as much as traditional low-fat, low-calorie regimes, leading to the assumption that it offers a healthier way of eating.

Yet there are questions. Low-carb diets have been linked to increased risk of heart attack, stroke and premature death, so while those on the Atkins diet will likely see weight loss, there may be hidden health costs.

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What is the Atkins diet? 

The Atkins diet is a weight loss plan developed in the 1960s by an American cardiologist, Dr Robert Atkins. It is a low-carbohydrate eating plan that gained popularity because it allows people to eat high levels of protein and fats, while severely restricting carbohydrates. The Atkins diet is a type of ketogenic diet, the goal of which is to reach a metabolic state called ketosis in which the body burns fat reserves instead of carbohydrates for fuel.

How does it work?

Dr Frankie Phillips is a dietitian at the British Dietetic Association (BDA) and explains:

“The diet is structured to be extremely low in carbohydrates. The body primarily gets energy in the form of glycogen by breaking down the easy carbohydrate stores in the body. Glycogen is stored in the muscles and liver as an easy-access energy store. Once that glycogen has been used up one of the effects will be weight loss, because for every gram of glycogen we lose, we also lose water that’s been stored alongside it.

“This is why when people go on a low-carb diet, it can be quite motivating because you see a lot of weight come off. If you stay on the Atkins diet for longer, a physiological process starts in which your body starts to break down fat stores to produce ketones as an energy source.”

Phases of the Atkins diet 

It’s always a good idea to consult a registered dietitian or GP before starting a new weight-loss diet plan.

Phase 1: Induction

This typically involves drastically reducing carbohydrates to around 20 grams a day, mainly from vegetables. This equates to one small banana. Instead, calories come from protein sources such as fish, meat, eggs, and cheese at every meal. Eight glasses of water a day are also recommended. This phase lasts for at least two weeks, depending on weight loss.

Phase 2: Balancing

In this phase, you keep eating a minimum of 12 to 15 grams of carbs a day from vegetables while continuing to eat protein as your main calorie sources and avoiding foods with added sugar. More sources of carbs such as berries, nuts, and seeds can be introduced. This phase lasts until you are around 10 pounds (4.5 kilograms) from your goal weight.

Phase 3: Pre-maintenance

In this phase, you slowly increase the range of foods you eat, including fruits, starchy vegetables and whole grains, adding 10 grams of carbs to your diet each week. You stay in this phase until you reach your goal weight.

Phase 4: Lifetime maintenance

Dr Atkins recommended adopting this way of eating for life.

Benefits/ claims of the Atkins diet

Atkins has three programmes, Atkins 20, Atkins 40 and Atkins 100, which, according to the Atkins website are designed to “flip the body’s metabolic switch” from burning carbs to burning fat.

It claims to be easier to follow than some other low carb diets and also provides more food choices and a better balance of protein, macronutrients, healthy fats, and fibre.

The Atkins diet claims a number of benefits including:

  • Prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and heart disease

  • Weight loss

  • Boosts energy

  • No calorie counting or portion control

  • Fat reduction

  • Blood sugar level maintenance

  • Filling

  • No exercise needed for weight loss

Dr Phillips says: “Some studies have shown that this very low carbohydrate type diet can have a beneficial impact on levels of good cholesterol levels while lowering the bad cholesterol levels.”

Bini Suresh, a registered dietitian, adds: “You can lose considerable amounts of weight, quite quickly which can be very motivating. The diet also encourages people to cut out most processed carbs and alcohol and provides clear phases and guidelines, making it structured and easy to follow for those who prefer structured approaches.”

Potential risks and criticisms 

  • Restricts dietary variation and limits intake of fruit and vegetables that are rich in nutritious compounds such as polyphenols, vitamins, and minerals

  • Restricts wholegrains, fibre and foods beneficial to the gut

  • Common ketosis side effects include nausea, dizziness, constipation, headache, fatigue and bad breath

  • Constipation

  • Risks associated with people with Type 2 diabetes. A 2018 report from the BDA states: “There is insufficient evidence to indicate that low carbohydrate diets are a superior or better approach than other strategies for weight loss. People with diabetes who are on certain drugs including insulin should be made aware of possible side effects such as the risk of hypoglycaemia or in rare cases ketoacidosis”, a serious complication of diabetes that can be life-threatening

  • Difficult for vegetarians to follow

  • According to a study, while high fat diets may provide short-term weight loss, risk of long-term hardening of the arteries outweighs the short-term benefits

  • A diet rich in animal protein can be expensive

  • Potential risk for disordered eating

  • A low-level carbohydrate diet with a high level of animal protein and fat was associated with a moderate increase in the risk of colon cancer among Chinese Singaporeans in a 2023 study

Foods to eat and avoid on the Atkins diet

Expert assessment

Dr Phillips concludes that those who follow the Atkins Diet will likely lose weight in the short term but risk putting the weight back on. “The body just goes back to storing the glycogen, storing the water alongside it and the weight goes back up,” she explains. “For longer-term weight loss and maintenance what makes the difference is simply the equation of energy in and energy out. If the amount of energy you are using overall is more than the amount you are putting in you will lose weight, regardless of whether the energy comes from carbohydrate, fat or protein.

“It is difficult to  follow the Atkins diet and live a social life, eating out and going to celebrations and eating with other people because it is a very restrictive diet.”

Suresh adds: “Personally, whether it’s improving heart health, reducing disease risk, losing weight or just improving your wellbeing, I would recommend following a balanced, non-restrictive diet that is rich in whole foods, includes an array of fresh fruits and vegetables, reduces ultra-processed foods and refined sugar, and does not include a list of ‘off-limit’ foods. The best diet for you is one that also includes all of your favourite foods in moderation.”

Comparison with other diets

The Atkins diet can be an effective way of losing weight compared with other diets. An analysis of randomised control trials into the impact of ketogenic diets in obese and overweight patients carried out by researchers at Ajou University, South Korea, concluded that ketogenic diets were more effective in improving weight control, especially in those with Type 2 diabetes, as compared to low-fat based diets. Their effects on other risk markers, such as blood pressure, inflammation and kidney function were comparable to those of low-fat diets. Researchers called for further studies to determine the long-term sustainability of ketogenic diets and whether they could reduce obesity related deaths.

According to the Mayo Clinic: “Most people can lose weight on almost any diet plan that restricts calories in the short term. Over the long term, though, studies show that low-carb diets like the Atkins diet are no more effective for weight loss than are standard weight-loss diets. And studies find that most people regain the weight they lost no matter which diet plan they used.

“Because carbs usually provide over half of calories consumed, the main reason for weight loss on the Atkins diet is lower overall calorie intake from eating less carbs. Some studies suggest that there are other reasons for weight loss with the Atkins diet. You may shed pounds because your food choices are limited. And you eat less since the extra protein and fat keep you feeling full longer. Both of these effects also contribute to lower overall calorie intake.”

Dr Phillips says that other diet plans which are similar but increase the percentage of carbs could be a better long-term option. A regular UK style diet consists of between about 45 per cent and 65 per cent carbs. Dr Phillips suggests a diet which provides about 30 per cent of the energy from carbohydrates could be easier to maintain and will still have some impact on metabolism.

Low-carb vegetable-based diets

“There has also been some more recent research looking at low-carb diets where the protein is predominantly from vegetable or plant sources, against more animal protein based low-carb diets and the plant option seems to offer a slightly healthier outcome than if you’re replacing your carbs with lots of animal proteins,” says Dr Phillips.

Suresh concludes that a better dietary option would be the Mediterranean diet which emphasises whole, minimally processed foods such as fruits, vegetables, whole grains, legumes, nuts, seeds, fish, and olive oil.

“It includes moderate amounts of lean proteins, such as poultry and dairy, and encourages regular physical activity. The Mediterranean diet has been associated with numerous health benefits, including improved heart health, weight management, and reduced risk of chronic diseases,” she says. “It’s important for individuals to choose a dietary approach that aligns with their preferences, health goals, and lifestyle factors.”