How low carb is low carb?

How few carbs are there in a low-carb diet? It depends. It depends on what you’re trying to achieve and who you are.

Low carb is often defined as any diet of below 130 grams of carbs per day. Generally speaking, the fewer carbs the more effective it appears to be for weight loss without hunger, or for reversing type 2 diabetes.1 Eating fewer carbs can also make the diet more restrictive and possibly more challenging.

At Diet Doctor we recommend recipes and meal plans for up to 100 grams of carbs per day. Here are three examples of how a low-carb dinner can look, depending on how many carbs you eat per day (the yellow stuff is delicious herb butter).


 

Ketogenic

Under 20 grams per dayStrict low carb

Moderate

20-50 grams per daymoderate low carb

Liberal

50-100 grams per dayLiberal low carb

 
 

Our definition

Here’s the way we define different levels of low carb at Diet Doctor:

  • Ketogenic low carb <20 gram carbs per day. This is a ketogenic diet (if protein intake is moderate).2 This level is defined as below 4 percent energy from carbs in our recipes, where we also keep the protein level low or moderate (excess protein is converted to carbohydrates in the body).345
  • Moderate low carb 20-50 grams of carbs per day. This level is defined as between 4-10 percent energy from carbs in our recipes
  • Liberal low carb 50-100 grams of carbs per day. This means 10-20 percent energy from carbs in our recipes

For comparison, a regular Western diet can easily contain 250 grams of carbs or more in a day, most of them refined carbs, including sugar.6

Fiber

The above numbers refer to digestible carbs, and discount the fiber.7 You can deduct them from your carb counts. For example, you can eat all the natural fiber you want from vegetables.8

Another word for digestible carbs, with the fiber deducted, is “net carbs”.

However, don’t be fooled by the label “net carbs” on processed products, like chocolate bars. That can be misleading, and these products are often full of sugar alcohols with potentially negative effects on your weight and blood sugar.9 If in doubt, avoid anything with the words “net carbs” printed on it.

An effective low-carb diet is ideally based on fresh, unprocessed food.10 Learn more

Guide: Carbohydrates on a low carb or keto diet
 

 

Keto recipes

Moderate recipes

Liberal recipes

How to choose

Some people may need to keep the carbs very low for maximum effect – a keto low-carb diet. This includes many people with significant weight issues, diabetes (mainly type 2) and food or sugar addiction, for example.11

Others – less carb-intolerant people – do great on a more liberal low-carb diet.12 This also lowers the risk of any side effects.

The third group – healthy, lean, active people – may not even need to eat very low carb, as long as they mainly eat unprocessed slow-acting carbs.

We believe many people may do best starting out on a strict keto diet, to experience the power of it.13 Later, as you hopefully approach your weight and health goals, you can try adding more carbs to see how much you tolerate.

Here’s a two-week guide to a strict low-carb diet

However, if avoiding most carbs does not feel possible for you, some health benefits can be had by just avoiding the worst carbs.14 Feel free to use the guide below for a more gradual start:

Eating better: Six steps down the carb mountain

Meal plans

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

Start free trial
 

 

More

Low carb for beginners

Low-carb recipes – marked ketogenic, moderate or liberal

A keto diet for beginners (strict low carb)

Low-carb basics videos

Visual guide

 

  1. 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]

    Low-carb diets can reduce hunger:

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

    Low-carb diets can 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

  2. A diet under 20 to 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]

  3. The limit of four percent energy from carbs means that you’ll stay below a maximum 20 grams of carbs on a 2,000-calorie diet, if you choose our keto recipes.

    In most cases you’ll end up with far fewer carbs than that, as some of the keto recipes you use are likely to have significantly less than the maximum amount of net carbs.

    Our keto recipes are also limited in protein. Our rule is that for keto recipes with 4 percent energy from carbs we accept a maximum of 25 energy percent protein. For lower carb levels we accept slightly more protein:

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

     
    If there’s too much protein in a recipe to classify it as keto low carb, we instead classify it as moderate low carb.

  4. 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]

  5. Previously we often called this level “strict low carb”, but as the word “keto” or “ketogenic” became commonly used we switched to only use this term, for simplicity.

  6. 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

    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]

    Journal of the American Medical Association 2002: The glycemic index. Physiological mechanisms relating to obesity, diabetes, and cardiovascular disease [overview article]

    British Medical Journal 1980: Rate of digestion of foods and postprandial glycaemia in normal and diabetic subjects [weak evidence]

  7. 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]

  8. 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.

  9. For example, 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]

  10. 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?

  11. 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]

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

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

    Who should NOT do a ketogenic diet?

  14. 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]