Intermittent fasting (IF) refers to structured eating patterns that cycle between periods of fasting and eating. The approach varies widely, from time-restricted feeding schedules such as 16:8 (fasting for 16 hours and eating within an 8-hour window) to alternate-day or modified fasting plans.

Research exploring intermittent fasting is ongoing. Studies have suggested potential effects on metabolism, blood sugar regulation, and inflammation, though findings remain mixed and depend on individual factors such as age, activity level, and medical history.

If you are considering intermittent fasting, it’s best to speak with your healthcare provider or a registered dietitian before beginning.

For those who already follow an intermittent fasting pattern, the foods chosen during eating windows can influence how steady energy levels feel and how well the body recovers from fasting periods. The following categories reflect research-informed guidance on foods that may help support balanced nutrition while fasting.

1. Protein-Rich Foods

Protein plays a central role in maintaining muscle mass and promoting satiety. Research suggests that distributing protein evenly throughout meals can help regulate appetite and blood sugar levels.

Examples:

• Eggs, poultry, fish, tofu, tempeh, and lentils
• Greek yogurt, cottage cheese, and plant-based protein powders
• Nuts and seeds as supplemental sources

Starting the first meal after fasting with a source of lean protein may help improve post-meal glucose response and reduce hunger later in the day.

2. High-Fibre Foods

Dietary fibre supports digestive health, helps manage cholesterol and glucose levels, and contributes to feelings of fullness. Incorporating both soluble and insoluble fibre can also promote smoother digestion after fasting periods.

Examples:

• Whole grains (oats, quinoa, barley, brown rice)
• Beans, lentils, and chickpeas
• Fruits such as apples, pears, and berries
• Vegetables like leafy greens, broccoli, and carrots

3. Healthy Fats

Healthy fats provide a slow, sustained energy source and aid in the absorption of fat-soluble vitamins (A, D, E, and K). Some studies have also associated unsaturated fats with cardiovascular benefits.

Examples:

• Avocado, nuts, and seeds (especially chia, flax, and hemp)
• Olive, avocado, and flaxseed oils
• Fatty fish such as salmon, sardines, or mackerel

4. Hydration and Electrolytes

During fasting periods, it’s common to confuse thirst with hunger. Maintaining hydration supports normal metabolic and cognitive function. Electrolytes, minerals like sodium, potassium, and magnesium, are also essential, particularly when fasting for longer durations.

Examples:

• Water (still or sparkling)
• Herbal teas such as mint or ginger
• Coconut water or low-sugar electrolyte drinks

A squeeze of lemon or a small pinch of salt in water can naturally replace minor electrolyte losses.

5. Complex Carbohydrates

When included during eating windows, complex carbohydrates supply glucose, the body’s primary energy source, while minimizing rapid spikes in blood sugar. Combining them with protein or fat can further stabilize energy levels.

Examples:

• Whole grains such as quinoa, oats, or farro
• Starchy vegetables like sweet potatoes or squash
• Legumes and lentils
• Low-glycemic fruits such as berries and citrus

6. Foods Gentle on Digestion

After fasting, the digestive system may be more sensitive to large or high-fat meals. Many people find it helpful to begin with a smaller, balanced meal or snack that includes fluids, protein, and carbohydrates before progressing to heavier foods.

Examples:

• Smoothies with protein, fruit, and leafy greens
• Greek yogurt with berries and chia seeds
• Vegetable soups or broths before the main meal

Fermented foods such as kefir, sauerkraut, and kimchi may also support digestive health through beneficial bacteria.

7. Foods to Limit

Certain foods and drinks may make fasting more difficult or cause fluctuations in blood sugar, leading to fatigue or irritability.

Examples to limit:

• Sugar-sweetened beverages and refined snacks
• Highly processed or fried foods
• Excess alcohol, especially when breaking a fast

Bringing It All Together

Intermittent fasting practices vary, and the evidence supporting their long-term effects continues to evolve. Regardless of fasting schedule, focusing on nutrient-dense, whole foods and staying hydrated can help support energy and overall health.

If you’re interested in trying intermittent fasting, consult your healthcare provider to ensure it aligns with your individual needs, medications, and lifestyle.