What Is the Ketogenic Diet?
The ketogenic (keto) diet is a very low-carbohydrate, high-fat eating pattern that shifts your body's primary fuel source from glucose to fat and ketones. By restricting carbohydrates to 20–50g of net carbs per day, liver glycogen depletes and the liver begins producing ketone bodies (beta-hydroxybutyrate, acetoacetate, acetone) from fatty acids — a metabolic state called nutritional ketosis.
In ketosis, fat — both dietary and stored body fat — becomes the primary fuel. This makes keto particularly effective for fat loss in people who respond well to carbohydrate restriction, and has applications in epilepsy management, blood glucose control, and cognitive performance.
Standard Keto Macro Ratios
| Macronutrient | % of Calories | Example (2,500 kcal) |
|---|---|---|
| Fat | 70–75% | 194–208 g |
| Protein | 20–25% | 125–156 g |
| Net Carbs | ~5% | ~25–30 g |
This calculator uses a protein-first approach — protein is set at 1.8 g per kg of lean body mass (LBM) to protect muscle, net carbs are fixed at 25 g to ensure ketosis, and fat fills the remaining calories from your TDEE. This approach prioritises body composition over a rigid macro percentage split.
Keto vs Standard Macro Calculator
The Macro Calculator distributes calories across protein, carbs, and fat according to your goal — maintaining 30–45% of calories from carbohydrates. Keto macros radically restrict carbs to ≤5% and replace that energy with fat. This shifts your metabolism into ketosis, which is fundamentally different from a standard balanced or low-carb diet.
Neither approach is universally superior — the best diet is the one you can maintain consistently. Research shows comparable long-term weight loss between keto and low-fat diets when total calories are matched. Keto may be preferable if you have difficulty with hunger on a calorie deficit, have insulin resistance or type 2 diabetes risk factors, or simply find high-fat foods more satisfying.
Net Carbs vs Total Carbs on Keto
Net carbs = total carbohydrates − dietary fibre. Dietary fibre is not digested and does not raise blood glucose or insulin, so it does not impair ketosis. On a standard keto diet, aim for:
- 25g net carbs/day — standard keto threshold, achieves ketosis for most people
- 50g net carbs/day — tolerated by some active individuals, particularly those doing high-intensity training
- 20g total carbs/day — used in strict or therapeutic keto protocols
Use the Keto Macros Guide for a detailed breakdown of net carbs across common foods and how to track them.
Scientific References: Mifflin MD, et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 51(2):241–247. — Bueno NB, et al. (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss. British Journal of Nutrition. 110(7):1178–1187.