Intermittent fasting has become an increasingly popular way to lose weight and improve health. It involves cycling between periods of eating and fasting. This allows the body to burn fat stores for energy during the fasting periods. One common question about intermittent fasting is how many calories you can eat during the eating periods and still lose weight. Here is a detailed look at calorie intake and intermittent fasting.
What is Intermittent Fasting?
Intermittent fasting (IF) is an eating pattern that involves regular fasting periods. Some popular approaches include:
- 16/8 method: Fast for 16 hours per day, eat during the remaining 8 hours.
- 5:2 diet: Eat normally 5 days per week, limit calories to 500-600 on 2 days.
- Alternate day fasting: Fast every other day.
- One meal a day (OMAD): Eat one meal per day.
Research shows intermittent fasting can:
- Lead to weight and body fat loss.
- Lower blood sugar, insulin and cholesterol levels.
- Increase longevity and cellular repair.
During the fasting periods, the body runs out of carbohydrates to use for energy. This causes a metabolic shift to using stored fat for fuel instead, resulting in weight loss.
Calorie Intake During Intermittent Fasting
Although intermittent fasting focuses more on when you eat rather than what you eat, calories still matter for weight loss. You need to burn more calories than you take in to lose weight.
Most studies on intermittent fasting set the calorie intake to about 70–100% of energy needs for weight maintenance. This creates a mild calorie deficit to promote weight loss.
For example, someone who needs 2,000 calories per day to maintain their current weight would eat 1,400–2,000 calories on intermittent fasting. The exact calorie target depends on your weight loss goals and the specific protocol used.
Typical Calorie Targets During Intermittent Fasting
| Intermittent Fasting Method | Example Calorie Target for Weight Loss* |
|---|---|
| 16/8 method | 1,400–1,800 calories |
| 5:2 diet | 500–600 calories twice weekly maintenance calories on other days |
| Alternate day fasting | 500–600 calories on fast days maintenance calories on feed days |
| One meal a day | All daily calories in one meal |
*Based on sample 2,000 calorie maintenance level
Factors That Affect Calorie Needs During Intermittent Fasting
Your individual calorie needs during intermittent fasting depend on:
- Gender: Women generally need fewer calories than men.
- Age: Calorie needs decrease as you get older.
- Activity level: Active individuals require more calories than sedentary people.
- Weight: People with more weight require more calories for maintenance.
- Height: Taller people usually need more calories than shorter people.
- Weight Goals: More significant weight loss requires a greater calorie deficit.
Use your total daily energy expenditure (TDEE) to estimate your calorie needs for weight loss with intermittent fasting. Then subtract 500–1,000 calories to lose about 1–2 pounds per week.
Foods to Eat While Intermittent Fasting
With intermittent fasting, what you eat is just as important as when you eat. Focus on nutritious whole foods during your eating periods:
Protein
Protein helps keep you full, maintains muscle mass and aids weight loss. Good protein sources include:
- Meat: Chicken, turkey, beef, pork, lamb.
- Fish: Salmon, tuna, trout, sardines.
- Eggs.
- Dairy: Greek yogurt, cottage cheese.
- Beans and legumes.
- Tofu and edamame.
- Protein powders like whey protein and pea protein.
Vegetables
Vegetables are low in calories and high in fiber and nutrients. Include all types of vegetables in your diet like:
- Leafy greens: Spinach, kale, lettuce, swiss chard.
- Cruciferous vegetables: Broccoli, cabbage, cauliflower, brussels sprouts.
- Starchy vegetables: Potatoes, sweet potatoes, winter squash, beets.
- Colorful vegetables: Carrots, tomatoes, peppers, mushrooms.
Fruits
Fruits are nutritious, antioxidant-rich foods. Enjoy fruits like:
- Berries: Strawberries, blueberries, raspberries.
- Apples, bananas, oranges, grapefruit.
- Melons: Cantaloupe, watermelon, honeydew.
- Stone fruits: Peaches, nectarines, plums, apricots.
- Tropical fruits: Mango, pineapple, guava.
Whole Grains
Choose whole grains like oats, quinoa, brown rice, barley and buckwheat instead of refined grains. They provide more fiber, protein and nutrients.
Healthy Fats
Include healthy fats like olive oil, avocados, nuts, seeds and omega-3 fats from fatty fish. Avoid saturated and trans fats.
Foods to Avoid or Limit During Intermittent Fasting
Some foods are not appropriate for intermittent fasting due to poor nutrition and the potential to trigger hunger and cravings.
Sugary Foods and Beverages
Avoid sugary desserts, sodas, juices, sports drinks, energy drinks, sweetened teas and coffee beverages. The blood sugar crash can increase hunger.
Refined Carbohydrates
Limit refined grains like white bread, white pasta and white rice. Also limit pastries, candy and other baked goods made with white flour.
Fried Foods
Fried foods like french fries, fried chicken, mozzarella sticks and potato chips are high in calories and unhealthy fats that will undermine your weight loss efforts.
Alcohol
Alcohol is high in empty calories and causes a loss of inhibition and willpower. It’s best to avoid alcohol or drink only small amounts like 1–2 drinks.
Ultra-Processed Foods
Avoid ultra-processed foods, convenience meals, fast foods and anything with lots of added sugar, fat and artificial ingredients.
Tips to Reduce Hunger on Intermittent Fasting
Hunger can be an issue with intermittent fasting, especially when first starting out. Here are some tips to help reduce hunger:
- Drink water, coffee, tea and other non-caloric beverages.
- Eat high protein foods, which are the most filling.
- Increase your vegetable intake.
- Eat slowly and stop when full.
- Distract yourself with activity or social interaction.
- Get adequate rest and manage stress.
As your body adapts, fasting becomes much easier both physically and mentally.
How to Determine Your Calorie Needs
There are several ways to estimate your calorie needs for weight loss with intermittent fasting:
TDEE Calculator
Use an online TDEE (total daily energy expenditure) calculator to get your maintenance calorie level. Then subtract 500–1,000 calories for weight loss.
Calorie Tracking App
Monitor your calorie intake and weight change for a couple weeks using an app like MyFitnessPal or Lose It. Adjust as needed to lose weight.
Measuring Resting Metabolic Rate
Get your RMR (resting metabolic rate) tested to determine your calorie needs. Cut 500–1,000 calories for weight loss.
Guided Diet Program
Follow a customized intermittent fasting program from a dietitian, doctor or health coach. They can provide calorie targets tailored to your needs.
Sample 1,500 Calorie Intermittent Fasting Diet Plan
Here is a sample 1,500 calorie intermittent fasting eating plan:
Breakfast
- Scrambled eggs with vegetables – 300 calories
- Oatmeal with berries – 250 calories
- Banana – 100 calories
- Coffee
Lunch
- Grilled chicken salad – 400 calories
- Broccoli soup – 120 calories
- Apple – 80 calories
- Iced tea
Dinner
- Turkey burger – 250 calories
- Roasted Brussels sprouts – 150 calories
- Quinoa – 150 calories
- Water
That provides around 1,500 calories with a balanced ratio of protein, healthy fats and complex carbs along with ample vitamins, minerals and antioxidants.
Conclusion
Following a calorie deficit is key for losing weight with intermittent fasting. Aim for a target around 70–100% of your maintenance needs, which is typically 1,400–1,800 calories per day for women and 1,600–2,000 for men.
Focus on protein, vegetables and other whole foods. Avoid added sugars, refined grains and unhealthy fats to curb hunger. Drink plenty of water and choose filling foods to make fasting periods easier.
With the right calorie target and healthy diet, intermittent fasting can help you lose weight effectively and improve your overall health.
