How low carb is keto?
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.
Under 20 grams per day(this meal: 6 grams)
Moderate low carb
20-50 daily carbs(this meal: 16 grams)
Liberal low carb
50-100 daily carbs(this meal, including
sweet potatoes: 37 grams)
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
Fiber and net carbs
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
What carb level to choose?
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.
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:
Meal plansGet lots of weekly keto meal plans, complete with shopping lists and more, with our premium meal planner tool (free trial).
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.
Ketogenic diets have been found to reduce appetite:
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:
A non-randomized trial with risk of financial bias shows remarkable effectiveness at reversing type 2 diabetes:
Adults in the US consume about 50% of their calories from carbohydrates, or about 250 grams of carbs per day if eating 2000 calories:
A diet under 20-50 grams of carbohydrates “typically leads to the presence of measurable ketones in the urine”:
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). ↩
Carbs, fats and protein are sometimes called your “macros” — the percentage of the three macro nutrients. ↩
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.
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.
Very high protein intake on a keto or low-carb diet may also lead to gluconeogenesis.
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]
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
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.
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. ↩
For instance, maltitol – a very common sweetener in low-carb products – has the highest glycemic (35) and insulinemic (27) indexes of all sugar alcohols.
About 60% of maltitol is digested and absorbed in the small intestine, like other carbs.
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.
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:
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:
Unless there’s a specific reason for you not to do this.
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. ↩
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:
Here are more studies and overview articles showing a connection between sugar, excess weight and disease:
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]