Keto Calculator — Ketogenic Diet Macros

Most ketogenic diets limit net carbs to 20–50 grams per day. "Net carbs" = total carbs minus fiber (and some subtract sugar alcohols). Staying under 20g net carbs is most effective for achieving ketosis, especially early on. As you adapt and become "fat-adapted" (usually 4–8 weeks), some people can increase carbs to 30–50g and remain in ketosis. Individual tolerance varies — if weight loss stalls, lower carbs further.

Most people enter ketosis within 2–4 days of restricting carbs to under 20–50g/day, provided glycogen stores are depleted. Exercise accelerates this — physical activity burns through glycogen stores faster. Signs you've entered ketosis: increased thirst and urination, "keto breath" (fruity/acetone smell), reduced appetite, initial headache/fatigue ("keto flu"), and eventually increased mental clarity and sustained energy. You can verify with urine ketone strips, breath meters, or blood ketone tests.

Keto flu is a collection of symptoms (headache, fatigue, brain fog, irritability, nausea) that occur during the first 1–2 weeks as your body transitions from burning glucose to ketones. It's largely caused by electrolyte loss — as insulin drops, kidneys excrete more sodium, taking potassium and magnesium with it. Prevention: drink plenty of water (3–4 liters/day), add salt to food, eat potassium-rich keto foods (avocado, leafy greens), and consider a magnesium supplement. Symptoms typically resolve within a week.