Keto Diet Explained: Macros, Benefits, Risks (2026)

What Is the Ketogenic Diet?

The ketogenic (keto) diet is a very low carbohydrate, high fat dietary approach that shifts the body into a metabolic state called ketosis. In ketosis, your liver converts fatty acids into ketone bodies (primarily beta-hydroxybutyrate, acetoacetate, and acetone), which become the primary fuel source for the brain and muscles instead of glucose.

Standard keto macros: approximately 70% of calories from fat, 25% from protein, and 5% from carbohydrates — typically 20–50g of net carbs per day (net carbs = total carbs minus dietary fibre).

The Clinical Evidence

Weight loss: Meta-analyses consistently show keto produces rapid initial weight loss (largely water and glycogen) followed by fat loss comparable to other calorie-restricted diets over 12 months. The 2022 Annual Review of Nutrition concluded that keto offers no meaningful metabolic advantage over other diets when calories and protein are equated.

Type 2 diabetes: Some of the strongest evidence for keto. Studies show meaningful reductions in HbA1c, fasting glucose, and insulin requirements in people with type 2 diabetes following keto. Some participants have achieved remission.

Epilepsy: The original medical application of keto, developed in the 1920s. Still used today for drug-resistant epilepsy, particularly in children, where it can reduce seizure frequency by 50% or more in approximately half of patients.

Benefits of the Keto Diet

• Rapid initial weight loss (primarily glycogen and water, then fat)
• Reduced appetite — ketones and high fat/protein intake strongly suppress hunger hormones
• Improved blood glucose control in type 2 diabetes
• Reduced triglycerides in most people
• Potential neurological benefits — being actively researched for Alzheimer's, Parkinson's, and traumatic brain injury

Risks and Limitations

• Keto flu: Fatigue, headache, brain fog, and irritability during the first 1–2 weeks of adaptation. Caused by electrolyte shifts as insulin drops and kidneys excrete sodium and potassium.
• Elevated LDL cholesterol in some individuals, particularly with high saturated fat intake
• Micronutrient deficiencies if variety is limited — particularly magnesium, potassium, and B vitamins
• Athletic performance — keto impairs high-intensity exercise performance that relies on glycolysis
• Social difficulty and long-term adherence challenges