Everything you need to start keto: how it works, exactly what to eat, the 7-day meal plan, how to beat the keto flu in 24 hours, and the predictable adaptation timeline.
What Is the Keto Diet?
The keto diet (short for ketogenic diet) is a very-low-carbohydrate, high-fat way of eating that shifts your body's primary fuel source from glucose to fat. By keeping carbohydrate intake under roughly 20-50 grams per day, the liver begins producing ketones - small molecules that your brain, heart, and muscles can burn for energy in place of sugar.
This metabolic state is called ketosis. It's the same state your body enters during fasting, prolonged exercise, or extended periods without dietary carbohydrate. The keto diet deliberately and sustainably produces it through food alone.
Keto in three numbers:
- Fat: ~70% of calories
- Protein: ~25% of calories
- Carbohydrate: ~5% of calories (20-50g/day)
Most people use keto for weight loss, blood sugar control, mental clarity, or as a medically supervised therapy for conditions like drug-resistant epilepsy.
How the Keto Diet Works: The 4 Stages of Adaptation
When you cut carbohydrates below your body's threshold for triggering ketogenesis, a predictable four-stage adaptation begins.
Stage 1: Glycogen Depletion (Days 1-3)
Your liver and muscles burn through stored glycogen. Each gram of glycogen is bound to 3-4 grams of water, which is why the scale drops sharply in week one - that's water loss, not fat loss. With the water goes a flood of sodium, potassium, and magnesium. Replacing them is the single most important task of the first 14 days.
Stage 2: Ketogenesis Begins (Days 3-7)
The liver starts converting fatty acids into three ketone bodies: beta-hydroxybutyrate, acetoacetate, and acetone. Hunger usually begins to flatten by day five.
Stage 3: Fat Adaptation (Days 7-30)
Your mitochondria upregulate the enzymes needed to efficiently burn fat. Energy stabilizes. Brain fog lifts. Cravings fade. This is the stretch most people abandon keto without ever experiencing, because they quit during Stage 1.
Stage 4: Metabolic Flexibility (Beyond Day 30)
Your body can switch between fat and glucose as needed without withdrawal symptoms. Extended fasting becomes easier. Mental endurance extends through long working hours.
How to Get Into Ketosis Fast: 7 Steps
Most people enter measurable ketosis within 2-4 days of starting the protocol. Here's the fastest path.
- Cut net carbs below 20 grams per day. Total carbs minus fiber. This is the threshold that reliably triggers ketogenesis in most adults.
- Eat 1g of protein per pound of target body weight. Excess protein converts to glucose through gluconeogenesis and slows entry into ketosis.
- Make fat 70% of your calories. Animal fats - butter, tallow, ghee, lard - are most stable. Avoid all industrial seed oils.
- Take 5-7 grams of sodium per day. Salt your food liberally. Drink salted broth. Your kidneys will excrete what you don't need.
- Drink water to thirst, not on a schedule. Excess water without salt dilutes sodium and worsens keto flu.
- Extend the overnight fast to 14-16 hours. Skip breakfast for the first two weeks. This accelerates glycogen depletion.
- Walk daily. Lift twice a week. Skip high-intensity exercise during the first two weeks - it doesn't speed adaptation and amplifies fatigue.
Signs You're in Ketosis
The most common question after the first week: am I actually in ketosis? The signs are usually obvious even without a meter.
- Reduced appetite. The most reliable signal. Many people forget to eat by day five.
- A metallic or fruity taste in the mouth. Acetone is exhaled in small amounts.
- Increased thirst and urination. Glycogen-bound water continues to release for the first 10-14 days.
- Improved mental clarity. Usually appears in week 2 once keto flu resolves.
- Stable energy without the post-meal slump. The 2pm crash disappears.
- Lower resting heart rate. Common in week 2-3 as adrenal function normalizes.