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How much protein can you have while fasting?

Intermittent fasting is an increasingly popular diet approach that involves alternating between periods of fasting and eating. Many people find it an effective way to lose weight and improve health. However, one common question is: how much protein can you eat during the fasting window?

The Role of Protein While Fasting

Protein is an important macronutrient that plays several key roles in the body:

  • Builds and repairs tissues and cells
  • Makes hormones, enzymes and other body chemicals
  • Helps maintain fluid balance
  • Transports nutrients and oxygen
  • Supports immune function

Getting adequate protein is especially important when fasting to preserve lean muscle mass. Some research shows that higher protein intake may also help curb hunger and cravings during the fast.

General Protein Recommendations

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. This equates to:

Body weight RDA protein (grams)
120 lbs (54 kg) 44
150 lbs (68 kg) 54
180 lbs (82 kg) 66

However, many experts recommend consuming more than the RDA, especially for those who are physically active or trying to lose weight. Common recommendations are:

  • 0.5-0.8 grams per pound of body weight
  • 90-120 grams per day
  • 15-25% of total daily calories from protein

Protein Needs While Fasting

During fasting periods, the goal is to get adequate protein to maintain muscle mass without consuming so many calories that it disrupts the benefits of fasting. Here are some general guidelines:

  • 0.8-1 gram per kilogram of body weight
  • 20-30 grams per meal
  • Maximum 50 grams per meal

The maximum of 50 grams per meal is recommended because protein is insulinogenic, meaning it can stimulate insulin release when consumed in large amounts. Since keeping insulin low is key during fasting periods, limiting protein per meal helps accomplish this goal.

Protein Timing

In addition to protein amount, timing can also influence results:

  • Early fasting window: Consume 20-30 grams of protein within 1-2 hours of starting your fast. This helps provide amino acids to minimize muscle breakdown.
  • Pre-workout: Have 20-40 grams protein before exercise to supply muscles.
  • Post-workout: Consume 20-40 grams protein after exercise to support recovery and growth.
  • Evenly spaced: Spread protein intake evenly throughout fasting periods to optimize muscle protein synthesis.

Good Protein Sources While Fasting

Choose high quality, nutrient-dense protein sources:

  • Lean meats: Chicken, turkey, lean beef
  • Fish: Salmon, tuna, sardines
  • Eggs
  • Greek yogurt
  • Cottage cheese
  • Protein powder
  • Beans, lentils
  • Tofu

Avoid highly processed meats like sausage, bacon, and deli meats – these are often high in preservatives like nitrates.

Sample Meal Plans

Here are examples of moderate and higher protein meal plans for a 150 pound person during 16:8 intermittent fasting:

Moderate Protein – 0.8g/kg (68g daily)

Meal Food Protein (g)
Meal 1 3 eggs + 1 cup cottage cheese 34
Meal 2 4 oz chicken + 1 cup veggies 26
Meal 3 Protein shake 25
Daily Total 68

Higher Protein – 1g/kg (82g daily)

Meal Food Protein (g)
Meal 1 Protein shake 25
Meal 2 6 oz salmon + 1 cup brussels sprouts 44
Meal 3 4 oz chicken + 0.5 cup cottage cheese 31
Daily Total 82

Tips for Getting More Protein

Having trouble getting enough protein in during fasting periods? Try these tips:

  • Eat protein-rich foods at each meal like Greek yogurt, eggs, fish and lean meat.
  • Have a protein shake if it’s hard to meet needs through food alone.
  • Choose higher protein options like Greek yogurt instead of regular.
  • Add extra protein to meals with whey, protein powder or nutritional yeast.
  • Cook with protein-rich ingredients like lentils, beans, quinoa and edamame.

Potential Pitfalls of Too Much Protein

While protein is important for fasting, consuming too much can cause issues:

  • Could kick you out of ketosis if doing keto
  • Difficult to digest large amounts of protein
  • Increased hunger and cravings
  • Higher insulin levels
  • GI discomfort, nausea
  • Dehydration
  • Risk of kidney problems

That’s why keeping protein moderate and spreading intake throughout the day is recommended.


Here are some key takeaways on protein intake while fasting:

  • Aim for 0.8-1g per kg body weight (68-82g for 150lb person)
  • 20-30g protein per meal is optimal
  • Distribute protein intake throughout fasting period
  • Time protein intake around workouts
  • Choose lean, minimally processed sources
  • Too much protein can reduce benefits of fasting

Getting the right amount of protein while fasting helps maximize muscle retention, curb hunger, and get optimal results. Focus on quality sources spaced throughout the day within the recommended guidelines.