How low carb is keto?

On a keto diet, how many carbs do you need to cut? How many carbs can you eat? The answer varies a bit depending on you as an individual and your goals.

In general: the fewer the carbs the bigger the impact might be on weight loss and reduction of cravings and hunger.1 If you have type 2 diabetes, the fewer carbs you eat, the faster your blood glucose and insulin resistance might improve.2 Some, however, find a very low carb diet too restrictive and challenging.

These three images, below, depict varying levels of carbs on a plate with a similar meal of steak, vegetables and salad with medallions of herb butter.

 

Ketogenic

Under 20 grams per dayKeto low carb(this meal: 6 grams)

Moderate low carb

20-50 daily carbsmoderate low carb(this meal: 16 grams)

Liberal low carb

50-100 daily carbsLiberal low carb(this meal, including
sweet potatoes: 37 grams)

 

The plate on the left would be ketogenic for most people. The other two, while very healthy, would not likely be ketogenic, but could still contribute to gradual weight loss and improved blood glucose and insulin sensitivity.3

We define low carb as anything under 100 grams per day. Note that a Western diet often has 250 grams of carbs per day, or even more.4

 
 

How we define low carb and keto

At Diet Doctor, we define the different levels of carbs this way:

  • Keto low carb: less than 20 grams of carbs per day. This level will be ketogenic for most people — if protein intake remains moderate.5 In our keto recipes, less than 4 per cent of total energy comes from carbs, and the rest will come from protein and fat.6 In keto recipes we also keep the protein level moderate, as excess protein can be converted to glucose in your body.7 Excess protein can also raise insulin, reducing ketosis.8 See note* below.
  • Moderate low carb: between 20 and 50 grams per day. In our moderate low carb recipes, energy derived from carbs will be between 4 to 10 per cent. The rest will come from protein and fat.
  • Liberal low carb: between 50 and 100 grams per day. In our liberal low carb recipes, energy derived from carbs will be 10 to 20 energy percent. The rest will come from protein and fat.

*Note: the limit of 4 per cent of energy coming from carbs in a ketogenic recipe means that if you are eating 3 meals a day, at a range of about 2,000 calories a day, you will stay below 20 grams of carbs. Many of our keto recipes will have you eating significantly less than the 20 grams of carbs each day

Our keto recipes also limit protein, as too much protein can be converted to blood sugar and may impact levels of ketosis.9 That means in recipes with a maximum 4 per cent of energy derived from carbs, protein is capped at 25 per cent of energy — and the rest, 71 per cent or more, is energy from fat.

If a keto recipe has lower carb percentages then recipes allow slightly more protein, keeping fat at a range of at about 70 per cent or more.10

If a recipe has too much protein, it will be classified as moderate low carb rather than keto.

Fiber and net carbs

Carb counts are the amount of digestible carbs, not counting the fiber.11 Fiber is subtracted from carb counts. You can eat all the fiber you want from keto vegetables, for example.12

Digestible carbs are also sometimes called “net carbs” but be very careful of this term on labels of low-carb products, processed foods, protein bars and energy/chocolate bars. Manufacturers often use “net carbs” as a way to disguise sugar alcohols that may slow weight loss and impact blood sugar.13 In fact, try to avoid any processed product that list “net carbs” on a label. Learn more about keto sweeteners

The most effective keto diet — and the healthiest — is likely based on real food.14 Learn more

 

What carb level to choose?

Do you need to stick to a keto diet, consuming under 20 grams of carbs a day? Or would you have good results with a moderate low carb diet, consuming 20 to 50 grams of carbs a day?

People with a lot of weight to lose, type 2 diabetes, insulin resistance, metabolic syndrome or sugar and/or food addiction, may find that they get their best results on a keto diet, keeping carbs very low.15 When starting out, however, they may experience keto side effects, like the keto flu, until they are adapted to burning more fat.

People who want to lose pounds but still have good insulin sensitivity, have less weight to lose, or still have good blood sugar levels can often do very well on a moderate or even liberal low carb diet.16 They are less likely to experience any side effects. Lean, active, and healthy individuals can also do very well on liberal low carb.

We believe many people may do best starting out on a strict keto diet.17 This will give you the best idea of whether you like how you feel, how it impacts you and what sort of results you get.18 Then, as you hopefully achieve your health and weight goals, you can decide whether to add more carbs back into your diet to a level where you feel your best and can maintain your health goals.

Here’s a two-week get-started guide to a keto diet

However, if you feel that avoiding most carbs is too hard, it’s also possible to get some health benefits by just avoiding the worst carbs.19 Perhaps this can be the right start for you? In that case, feel free to use the guide below:

Eating better: Six steps down the carb mountain

Meal plans

Get lots of weekly keto meal plans, complete with shopping lists and more, with our premium meal planner tool (free trial).
 

 
 

More

A ketogenic diet for beginners
14-day keto diet plan and menu
Ketogenic diet foods – what to eat and what to avoid

 

Visual guide

 

  1. The idea that fewer carbs is always more effective is mainly based on the consistent experience of experienced practitioners, and stories from people trying different levels of carb restriction [weak evidence]

    The only intervention study – to our knowledge – that compared different levels of carb restriction was a small trial that found trends towards greater weight loss and greater improvements in cardiometabolic risk factors as carb intake went lower.

    PeerJ 2019: Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: a randomised clinical trial [moderate evidence]

    Ketogenic diets have been found to reduce appetite:

    Obesity Reviews 2014: Do ketogenic diets really suppress appetite? A systematic review and meta-analysis [strong evidence]

    Obesity (Silver Spring) 2011: Change in food cravings, food preferences, and appetite during a low-carbohydrate and low-fat diet. [moderate evidence]

  2. Glycemic control appears to improve more the lower carb intake is:

    Journal of the American Dietetic Association 2008: Restricted-carbohydrate diets in patients with type 2 diabetes: a meta-analysis [moderate evidence, downgraded as it’s comparing effects between different low-carb trials. There is no RCT comparing low carb to lower carb.]

    This is also based on the consistent experience of experienced practitioners, and stories from people trying different levels of carb restriction [weak evidence].

    Low-carb diets has been shown to help reduce or even normalize blood sugar, and thus potentially reverse type 2 diabetes:

    Diabetes Research and Clinical Practice 2018: Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis [strong evidence]

    BMJ Open Diabetes Research and Care 2017: Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes [strong evidence]

    A non-randomized trial with risk of financial bias shows remarkable effectiveness at reversing type 2 diabetes:

    Diabetes Therapy 2018: Effectiveness and safety of a novel care model for the management of type 2 diabetes at 1 year: An open-label, non-randomized, controlled study [weak evidence]

    Full list of studies on low carb for diabetes

  3. Diabetes Research and Clinical Practice 2018: Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis [strong evidence]

    Annals of Internal Medicine 2014: Effects of low-carbohydrate and low-fat diets: a randomized trial [moderate evidence]

  4. Adults in the US consume about 50% of their calories from carbohydrates, or about 250 grams of carbs per day if eating 2000 calories:

    Centers for Disease Control and Prevention

  5. A diet under 20-50 grams of carbohydrates “typically leads to the presence of measurable ketones in the urine”:

    The American Journal of Clinical Nutrition 2007: Low-carbohydrate nutrition and metabolism [overview article]

    Note that higher levels of carb intake also can be ketogenic in some people, depending on their metabolism and activity level (increased activity can contribute).

  6. Carbs, fats and protein are sometimes called your “macros” — the percentage of the three macro nutrients.

  7. The process of converting excess protein to glucose is called gluconeogenesis (literally “making new glucose”). During digestion, protein is broken down into individual amino acids, which your body can use to make glucose.

    International Journal for Vitamin and Nutrition Research 2011: Protein turnover, ureagenesis and gluconeogenesis [overview article]

  8. Diabetes Care 1991: Plasma glucose and insulin response to macronutrients in nondiabetic and NIDDM subjects [overview article]

  9. Gluconeogenesis is a demand-driven process that occurs whenever glucose is needed. For instance, when someone follows a carb-free diet, gluconeogenesis will provide glucose for the few parts of the body that can’t use ketones: red blood cells and portions of the kidney, eye and brain.

    American Journal of Clinical Nutrition 2009: Gluconeogenesis and energy expenditure after a high-protein, carbohydrate-free diet [moderate evidence]

    Very high protein intake on a keto or low-carb diet may also lead to gluconeogenesis.

    Diabetologia 2000: Effect of long-term dietary protein intake on glucose metabolism in humans [moderate evidence]

    However, reports from physicians who recommend a higher-protein, low-carb way of eating suggest that blood sugar response to this approach can vary quite a bit from person to person. [weak evidence]

  10. Here are the exact protein limits we use to classify recipes as keto:

    • 4 % carbs = max 25 % protein
    • 3 % carbs = max 27 % protein
    • 2 % carbs = max 29 % protein
    • 1 % carbs = max 31 % protein
    • 0 % carbs = max 33 % protein

  11. Although some low-carb experts disagree, it’s generally accepted that humans lack the enzymes needed to break down fiber and absorb it into the bloodstream. Therefore, the fiber portion of carbs does not raise blood sugar and insulin levels.

    Nutrients 2010: Effects of dietary fiber and its components on metabolic health [overview article]

  12. Fiber does not directly affect blood sugar levels, though it can indirectly slow down the absorption of digestible carbohydrates that you eat.

    Fiber can have both beneficial and some potential negative effects on gut health, but it usually has no major impact on the effects of a low-carb diet.

  13. For instance, maltitol – a very common sweetener in low-carb products – has the highest glycemic (35) and insulinemic (27) indexes of all sugar alcohols.

    Nutrition Research Reviews 2003: Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties [overview article]

    About 60% of maltitol is digested and absorbed in the small intestine, like other carbs.

    Gastroenterology 1990: Digestion and absorption in the human intestine of three sugar alcohols [moderate evidence]

    Gastroentérologie Clinique et Biologique 1991: Clinical tolerance, intestinal absorption, and energy value of four sugar alcohols taken on an empty stomach [moderate evidence]

  14. This is mainly based on evolutionary theories and clinical experience. [weak evidence]

    Focus on eating good quality, minimally processed real food. Ideally the food you buy shouldn’t even have a list of ingredients (or it should be very short).

    Unprocessed real food is what our ancestors have been eating for millions of years, and what the human animal is evolutionarily adapted to. By introducing processing, e.g. refining carbohydrates in a way that increases the speed of absorption and reduces the amount of nutrients and fiber, we change the food into something our bodies may not be adapted to, i.e. we introduce an unknown risk of side effects.

    Learn more: What are you designed to eat?

  15. This is mainly based on the consistent experience of experienced practitioners, and stories from people trying different levels of carb restriction [weak evidence]

    The only small intervention study – to our knowledge – that compare different levels of carb restriction found trends towards a larger effects with fewer carbs, for weight loss and cardiometabolic risk factors. However, these trends did not reach statistical significance:

    PeerJ 2019: Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: a randomised clinical trial [moderate evidence]

    Regarding sugar/food addiction, this is likely mostly caused by avoiding the foods that can cause a food addiction, most of which are processed foods full of sugar and/or other refined carbohydrates.

    Just like with any other addiction, avoiding the cause is a necessary part of slowly reducing the addiction. A person who is addicted to alcohol normally can’t consume alcohol “in moderation” and be successful. The same thing is likely true for any addiction. [clinical experience, weak evidence]

    In the case of the keto diet, it may also be that the hunger-reducing effect can be helpful:

    Obesity Reviews 2014: Do ketogenic diets really suppress appetite? A systematic review and meta-analysis [strong evidence]

    Frontiers in Psychology 2015: Ketosis, ketogenic diet and food intake control: a complex relationship [overview article]

  16. PeerJ 2019: Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: a randomised clinical trial [moderate evidence]

  17. Unless there’s a specific reason for you not to do this.

    Who should NOT do a ketogenic diet?

  18. It can also be helpful to experience it, as it’s a good way to shed a few pounds if weight ever creeps up or weight loss stalls.

  19. Whether people go on a low-carb or a low-fat diet, they tend to lose weight as long as they minimize sugar and refined flours in their diet:

    JAMA 2018: Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion [moderate evidence] (analysis)

    Here are more studies and overview articles showing a connection between sugar, excess weight and disease:

    JAMA Internal Medicine 2014: Added sugar intake and cardiovascular diseases mortality among US adults [weak evidence]

    Nutrition & Metabolism 2005: Fructose, insulin resistance, and metabolic dyslipidemia [overview article]

    The American Journal of Clinical Nutrition 2007: Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease [overview article]