Net carbs, and how slotho rates a food for keto
Whether a food fits a ketogenic diet is hard to judge from a label. slotho shows a keto rating on every food whose label declares its macronutrients: the word Keto followed by up to three stars.
DISCLAIMER: This article explains how the app calculates keto ratings and is NOT medical advice. This is not a comprehensive explanation of the ketogenic diet or its health implications. The app is a tool to help users understand the macronutrient composition of foods, not a substitute for professional medical guidance. Always consult with a healthcare provider or registered dietitian before starting any diet, including a ketogenic diet.
What a ketogenic diet is
The ketogenic diet is a high-fat, moderate-protein, and low-carbohydrate eating plan designed to put your body into ketosis—a metabolic state where your body burns fat for fuel instead of glucose.
Standard ketogenic diet macronutrient ratios typically fall around:
- 70-75% of calories from fat
- 20-25% of calories from protein
- 5-10% of calories from carbohydrates
The keto stars
The more stars, the smaller the share of a food’s calories that comes from carbohydrate:
- Three stars: under 10% of calories from carbohydrate
- Two stars: 10% to under 20%
- One star: 20% to under 40%
- No stars: 40% or more
A food whose label declares none of carbohydrate, fat or protein gets no rating at all, rather than one it has not earned.
How the rating is calculated
slotho works out what share of a food’s calories comes from carbohydrate, from the values per 100 g on its label.
Step 1: work out where the calories come from
For each food, slotho:
- Multiplies carbohydrate grams by 4 calories/gram
- Multiplies protein grams by 4 calories/gram
- Multiplies fat grams by 9 calories/gram
Step 2: find the carbohydrate share
Carbohydrate share = (carbohydrate calories ÷ total calories) × 100.
Step 3: count the stars
The stars follow that share, using the thresholds above. Fat and protein count only through the calories they add: a food rich in fat has a smaller carbohydrate share, and so more stars.
How to use the ratings
The keto stars in slotho can help you:
- Quickly identify suitable foods for your ketogenic diet
- Compare different food options for their keto compatibility
- Make informed choices when shopping for groceries
- Plan meals that maintain your desired macro ratios
You can also sort search results by Keto-Friendly, which puts the foods with the most stars first. Because the rating is a share of calories, it does not change with portion size.
Common questions
Why might a food I consider keto-friendly get fewer stars?
The rating looks only at where a food’s calories come from. Some foods keto dieters eat in small amounts get fewer stars because much of their energy is carbohydrate; the rating does not know how much of it you eat.
How does the app get the nutritional information for foods?
From three places: the public Open Food Facts database, USDA FoodData Central, and slotho’s built-in library of common foods. The rating is only as good as the label behind it.
How does the keto rating relate to the other nutritional ratings in the app?
The keto rating is independent of other nutritional scores like Nutri-Score or NOVA. A food could have an excellent keto rating but a poor overall nutritional score, or vice versa.
Net carbs
The stars are worked out from total carbohydrate, not net carbs. slotho does show net carbs separately: a Net carbs row appears on a food whenever its label declares both carbohydrate and fibre. Net carbs, and how to work them out covers the formula, the sugar-alcohol exception and the UK/US labelling trap that makes people subtract twice.
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