Manage weight and metabolic health by focusing on when you eat, not just what you eat.
Your Protocol — 16:8
Recommended workout window: 11:00 AM – 1:00 PM. Training near the end of your fast (or right as your eating window opens) combines the fat-oxidation benefit of fasted training with the ability to refuel with protein soon after — see "Fasting & Your Workout" below for why this timing matters.
Find Your Fasting Protocol
Answer a few questions and get a window suggestion plus a workout timing tip based on your answers.
1. How experienced are you with fasting?
2. What's the main goal?
3. How do you handle skipping meals?
4. When do you prefer to work out?
How It Works
After hours without food, the body works through its glycogen (sugar) stores and shifts toward burning fat for fuel — a process called metabolic switching. This shift generally begins once glycogen runs low, several hours into a fast.
If you eat throughout the day without a deficit or activity to draw on those calories, your body tends to burn what you just ate rather than dip into fat stores. Intermittent fasting works by extending the window your body spends past that "just-eaten" state.
Ground Rules
Adjustment Period
It can take 2–4 weeks for your body to adjust to a fasting routine. Most people find that once they're past this window, it gets easier to stick with and they report feeling better overall.1
Benefits
Hormone Regulation
Supports healthier insulin and leptin signaling (see hormone breakdown below).
Lower Insulin Levels
Extended fasting windows are associated with reduced circulating insulin.
Blood Pressure & Resting Heart Rate
Several studies link time-restricted eating to modest improvements in both.
Digestive Rest
Gives the digestive system an extended break between meals.
Verbal Memory
Caloric restriction has shown improved verbal memory scores in clinical trials.
Mostly studied in adults 60+Fat Loss, Muscle Preserved
Associated with fat loss while maintaining lean muscle mass better than continuous restriction in some studies.
The Hormone Mechanics
Leptin regulates energy balance by signaling fullness and inhibiting hunger, which in turn limits fat storage in adipocytes. The amount of leptin in your blood tracks closely with how much body fat you carry — and leptin resistance can cause you to feel hungry and keep eating even when your body has plenty of stored fat.
Adiponectin is a hormone released by fat tissue that supports insulin sensitivity and helps regulate inflammation. Higher adiponectin and lower leptin levels are generally markers of better metabolic health.
Fasting and diet quality can help lower glucose, insulin, and leptin while raising adiponectin — improving insulin resistance in the process. Diet-based interventions have shown improvements in insulin resistance markers comparable to metformin in some studies2 — this is meaningfully different from a fast reversing a need for prescribed insulin therapy, which is a decision to make with a doctor, not a diet alone.
What Supports Healthy Leptin & Adiponectin
Increasing physical activity, getting enough sleep, decreasing sugar intake, and including more fish in your diet can improve leptin sensitivity.
Fasting & Your Workout
Cardio: Training fasted depletes glycogen faster, which shifts your body toward burning more fat during the session. A 2016 study comparing fasted vs. fed morning runners found the fasted group had higher fat oxidation and lower overall energy intake for the day.4
Strength training: Lifting fasted is fine, but glycogen stores are already low going in — prioritize a protein-containing meal soon after a heavy session to support muscle repair. This is a good reason to time lifting sessions near the end of your fasting window rather than the middle of it.
If muscle-building is the priority: Some research suggests fasting's less-frequent feeding pattern may be a suboptimal strategy for maximizing muscle protein synthesis compared to spreading protein across more meals.5 If gaining muscle is the main goal, a wider eating window (14:10 or 12:12) may serve you better than a narrow one.
Myth Check
Fasting over several days is dangerous because your body starts storing more fat in response to starvation.
This isn't how it works. What actually happens is metabolic slowdown (adaptive thermogenesis) — your body becomes more efficient with energy, it doesn't switch into fat-storage mode. The real risks of multi-day fasting are muscle/lean-mass loss, electrolyte imbalances, and cardiac strain, which is why extended fasts should be medically supervised.3
Improving insulin resistance through diet can reverse the need for insulin therapy.
Diet can meaningfully improve insulin sensitivity — some studies show effects on insulin resistance markers comparable to metformin. But stopping or changing prescribed insulin therapy is a medical decision that should go through a doctor, not something diet alone determines.2
Sources