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Atkins Diet Guide

An honest guide to Atkins: what the big trials found, how the four phases work, how to do it safely, a phase-by-phase food list, and 27 recipes with the nutrition worked out.

Taking medication for diabetes or blood pressure? Talk to your GP before starting Phase 1. Doses often need to be reduced quickly. See Safety & kit.

What is the Atkins diet?

Atkins is a low-carbohydrate diet created by cardiologist Dr Robert Atkins in the 1970s. Unlike keto, it's designed to change over time. You start very low-carb to kick-start weight loss, then add carbs back step by step until you find the most you can eat while still losing, then maintaining, weight.

Net carbs = total carbohydrate minus fibre. Atkins counts net carbs, because fibre isn't digested into sugar.

The four phases of classic Atkins (Atkins 20)

Phase 1: Induction

20–25 g net carbs/day

At least 2 weeks. Protein at every meal, healthy fats, and 12–15 g of carbs from "foundation" vegetables such as leafy greens, broccoli and zucchini. No fruit, grains, nuts or alcohol.

Phase 2: Balancing

Add 5 g a week

Nuts, seeds, berries, more vegetables and soft cheeses come back, lowest-carb first. You keep adding carbs until weight loss slows. Continue until you're about 5 kg (10 lb) from your goal.

Phase 3: Pre-maintenance

Add ~10 g a week

Fruit, starchy vegetables, legumes and whole grains are carefully added back, one at a time. You find your personal "carb balance": the most you can eat without regaining.

Phase 4: Lifetime

Your own level (often 40–100 g+)

Keep eating at your carb balance long term. If weight creeps back, drop down a phase for a while.

Today's Atkins plans

Atkins 20Starts at 20 g net carbs/day
The classic four-phase plan above. Aimed at people with a lot of weight to lose (roughly 18 kg / 40 lb or more), or with prediabetes or type 2 diabetes.
Atkins 40Starts at 40 g net carbs/day
For people with less weight to lose who want more food variety from day one. Carbs go up 10 g at a time as you near your goal.
Atkins 100About 100 g net carbs/day
A moderate lower-carb lifestyle plan for maintaining weight or losing slowly. Atkins suggests this one for pregnancy and breastfeeding, with your doctor's OK.

Our food list and recipes are tagged by Atkins 20 phase, which is the most detailed version. If you're on Atkins 40 or 100, you can generally eat Phase 2 or Phase 3 foods from the start.

What does the research actually show?

Atkins is one of the most-studied diets in the world, and it has been tested by name in several large randomised trials. Here's what they found, with the study type and size shown. Tap a topic to open it.

Strong consistent results from randomised trials Moderate good trials, some limits Mixed benefits and trade-offs
Gardner et al., 2007 — JAMA ("A TO Z" study, Stanford)
Randomised controlled trialn = 311 overweight women12 months

Four popular diets were compared head to head. After a year, the Atkins group lost 4.7 kg, compared with 2.6 kg on LEARN (a standard lifestyle program), 2.2 kg on Ornish (very low fat) and 1.6 kg on the Zone. Atkins also gave the best results for triglycerides and HDL cholesterol.

Foster et al., 2003 — New England Journal of Medicine
Randomised controlled trialn = 6312 months

The Atkins group lost more weight than the low-fat group at 3 and 6 months. By 12 months the gap was no longer statistically significant. Triglycerides and HDL improved more on Atkins.

Takeaway: Atkins tends to produce faster weight loss early on than low-fat diets. Many people find the quick early results motivating.
Shai et al., 2008 — New England Journal of Medicine ("DIRECT" trial)
Randomised controlled trialn = 3222 years (85% completed)

In a workplace cafeteria study, an Atkins-based low-carb diet led to 4.7 kg of weight loss after two years. That compares with 4.4 kg on a Mediterranean diet and 2.9 kg on a low-fat diet. The low-carb group had the biggest improvement in the cholesterol-to-HDL ratio (about 20%), with HDL up about 20% and triglycerides down about 14%.

Foster et al., 2010 — Annals of Internal Medicine
Randomised controlled trialn = 3072 years

Both low-carb and low-fat groups (with the same intensive behavioural support) lost about 7% of their body weight at two years, with no difference between them. The low-carb group had a significantly bigger rise in HDL cholesterol. In the early months, the low-carb group reported more bad breath, hair loss, constipation and dry mouth.

Takeaway: after 1–2 years, Atkins does about as well as other well-supported diets, and sometimes a little better. Its lasting advantage shows up mostly in triglycerides and HDL.
Johnston et al., 2014 — JAMA
Network meta-analysis of 48 randomised trialsn = 7,2866 and 12 months

Compared with no diet, low-carb diets led to about 8.7 kg of weight loss at 6 months and low-fat diets about 8.0 kg. By 12 months both were about 7.3 kg. Atkins beat the Zone diet by about 1.7 kg at 6 months. The authors concluded the differences between named diets were "small and unlikely to be important".

Takeaway: there's no magic brand. Atkins works well, and so do several others. The one you can stick with is the one that works for you.

Across the trials above, the pattern is very consistent: triglycerides fall and HDL rises more on Atkins than on low-fat diets. LDL is the one to watch. In a meta-analysis of 13 trials (Bueno 2013), very-low-carb diets raised LDL slightly more than low-fat diets (+0.12 mmol/L), and some individuals see much larger rises.

Jenkins et al., 2014 — BMJ Open ("Eco-Atkins")
Randomised controlled trialn = 39 completed6 months

A plant-based low-carb diet (protein and fat from nuts, soy, gluten and vegetable oils rather than meat and butter) led to 6.9 kg of weight loss, compared with 5.8 kg on a high-carb diet. It also lowered LDL by about 0.49 mmol/L more. However, half the low-carb group dropped out.

Takeaway: get a cholesterol test before you start and after about 3 months. If LDL rises, lean towards fish, poultry, eggs, olive oil, avocado and nuts, and go easier on butter, cream and fatty processed meats.
Goldenberg et al., 2021 — BMJ
Meta-analysis of 23 randomised trialsn = 1,3576 and 12 months

At 6 months, low-carb diets led to about 32 more people out of every 100 reaching diabetes remission (HbA1c under 6.5%) than control diets, plus extra weight loss. By 12 months the advantages had largely faded.

Takeaway: Phase 1 is low enough in carbs to cut blood sugar quickly, so diabetes medicines often need to be reduced before you start. Atkins itself recommends Atkins 20 for people with type 2 diabetes, but only with medical supervision.

The trials above tested Atkins as a whole. None tested whether the four-phase structure, adding carbs back in 5 g steps, works better than simply choosing a moderate carb level from the start. What the phases do offer is a structured way to find your own carb tolerance and move towards a more varied diet you can keep up. That's the biggest weakness of most diets, including strict keto.

Takeaway: treat the phases as a practical tool rather than a proven formula. If Phase 1 feels too hard, Atkins 40 is a gentler start.

The bottom line

  • Atkins is one of the best-tested diets there is. It reliably produces faster early weight loss than low-fat diets, and about equal results by 1–2 years.
  • It consistently improves triglycerides and HDL, and can quickly improve blood sugar. LDL is worth monitoring.
  • Early side effects (bad breath, constipation, "induction flu") are common but usually short-lived.
  • Its biggest strength is the step-by-step path back to a varied diet. Use the phases to find a carb level you can live with long term.

References

  1. Gardner CD et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study. JAMA 2007;297:969–77.
  2. Foster GD et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 2003;348:2082–90.
  3. Shai I et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med 2008;359:229–41.
  4. Foster GD et al. Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial. Ann Intern Med 2010;153:147–57.
  5. Johnston BC et al. Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. JAMA 2014;312:923–33.
  6. Bueno NB et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr 2013;110:1178–87.
  7. Jenkins DJA et al. Effect of a 6-month vegan low-carbohydrate ("Eco-Atkins") diet on cardiovascular risk factors and body weight in hyperlipidaemic adults: a randomised controlled trial. BMJ Open 2014;4:e003505.
  8. Goldenberg JZ et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission. BMJ 2021;372:m4743.
  9. Atkins Nutritionals — Atkins 20, 40 and 100 program descriptions (atkins.com); Mayo Clinic — Atkins Diet: what's behind the claims?

Frequently Asked Questions

Phase 1 of Atkins is essentially a ketogenic diet (about 20 g net carbs a day). The difference is what happens next. Keto aims to stay in ketosis long term. Atkins deliberately adds carbs back through its phases until you find your personal carb balance, often 40–100 g a day in maintenance. Atkins also tends to be a little higher in protein.

At least two weeks. Some people stay longer if they have a lot of weight to lose and feel well. If you have less to lose, or find Phase 1 very hard, you can move on sooner or start with Atkins 40 instead.

In Phase 2, add about 5 g of net carbs a week, trying one new food at a time, and watch the scale. When weight loss stalls for a couple of weeks, or cravings return, step back 5 g. That's roughly your limit for losing weight. Your limit for maintaining (Phase 3–4) is usually higher.

In the major trials, Atkins improved triglycerides and HDL cholesterol more than low-fat diets, and blood pressure generally improved with weight loss. LDL cholesterol rose slightly on average, and a lot in some people. That's why a cholesterol test before and after about 3 months is sensible. Choosing fish, poultry, olive oil, nuts and avocado over lots of butter and processed meat helps.

No. They're convenient, but all the trials above used ordinary food. Many "low-carb" treats contain sugar alcohols like maltitol that can raise blood sugar and upset your stomach. Treat them as an occasional backup, not the basis of the diet.

Not in Phase 1. From Phase 2, small amounts of dry wine or spirits with soda water fit. Your body burns alcohol before fat, so it will slow your progress. Beer and sugary mixers are high in carbs.

iPhone: open this page in Safari, tap Share, then "Add to Home Screen". Android: open it in Chrome, tap ⋮, then "Add to Home screen". It gets its own icon, and your phase, ticked foods and shopping list are remembered on that phone.

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Disclaimer: This guide is general information based on published research. It is not medical advice and doesn't replace advice from your GP, specialist or an Accredited Practising Dietitian. Atkins® is a registered trademark of Atkins Nutritionals, Inc. This guide is independent and not affiliated with or endorsed by Atkins. Talk to your doctor before starting, especially if you take medication for diabetes or blood pressure. Nutrition values are estimates.