How Ketosis Works
When carbohydrate intake drops below roughly 20-50 grams per day, the liver converts fatty acids into ketone bodies; primarily beta-hydroxybutyrate, acetoacetate, and acetone. These ketones replace glucose as the primary fuel for the brain and muscles. The metabolic switch typically occurs within 24-72 hours of carbohydrate restriction, though full fat adaptation, where athletic performance returns to baseline, can take four to eight weeks.
The Four Keto Variants Explained
Standard Keto (SKD) maintains a constant 70/25/5 fat-protein-carb ratio. High-Protein Keto (HPKD) raises protein to 30% for those who train with weights. Targeted Keto (TKD) adds 20-50 grams of fast-digesting carbs around workouts to support glycolytic exercise. Cyclical Keto (CKD) alternates five strict keto days with one or two higher-carb refeed days, often favored by strength athletes and bodybuilders.
Matching Macros to Your Phase
During the adaptation phase, very low carbs and moderate protein ease the transition into ketosis. In the fat-loss phase, a caloric deficit of 15-25% below TDEE accelerates lipolysis while protein stays high enough to protect lean mass. The maintenance phase matches calories to TDEE. The performance phase nudges calories slightly above TDEE and may increase peri-workout carbs for athletes pursuing strength or endurance gains.
Net Carbs, Fiber, and Staying in Ketosis
Tracking net carbs instead of total carbs lets you eat fiber-rich vegetables without worrying about being kicked out of ketosis. Soluble fiber feeds beneficial gut bacteria, while insoluble fiber supports digestive regularity. Most ketogenic guidelines recommend 20-25 grams of net carbs per day during strict phases and up to 50 grams during maintenance. A ketone meter or urine strips can confirm you remain in the target 0.5-3.0 mmol/L range.
