Your Guide to Intermittent-Fasting Macros

Written and medically reviewed by Nicole Grant, RD

It’s no secret that the typical American diet is prone to excessive amounts of unhealthy fats, sugars, and processed foods, while lacking in essential nutrients like fiber, protein, vitamins, and minerals. This imbalance can lead to health issues such as type-2 diabetes, heart disease, and nutrient deficiencies. A significant portion of Americans struggle to maintain a balanced diet due to factors such as accessibility, affordability, and subpar education surrounding nutrition.

Pursuing a nutritionally well-rounded diet is part of a holistic approach to health that can include intermittent fasting (IF). Intermittent fasting is shown to contribute to improved weight management, enhanced metabolic health, increased insulin sensitivity, and potential longevity benefits. It may also support brain health, boost energy levels, and, in the long run, actually simplify a person’s approach to healthy eating. 

IF is a great approach for achieving weight-loss and health benefits, but sometimes you want more — and that’s where taking a closer look at your nutrition and macronutrients (macros) can come into play. Intermittent fasting and hitting your macros can easily go hand in hand once you arm yourself with a solid understanding of what macros are, plus how (and when) to target the important ones.

Read on for the tools you need to create a more balanced approach to a healthy and sustainable diet that’s compatible with time-restricted eating. 

What Are Intermittent-Fasting Macros?

No matter your reasons for following an IF lifestyle, and whatever length of fast you choose, it’s important to consume balanced macronutrients during your eating window. You’ll find that a diet that includes adequate protein, healthy fats, and carbohydrates from whole foods perfectly complements any fasting practice.

The specific macronutrient distribution can vary based on individual goals, preferences, and activity levels. You may opt for higher carbohydrate intake to support your athletic endeavors, whereas others might choose to emphasize healthy fats to better manage blood-sugar control.

How to Calculate Macros for Intermittent Fasting

If you fast regularly, targeting macros depends on a variety of factors including fitness goals, activity levels, and personal preferences. However, a common approach is to focus on balanced macronutrient distribution during eating windows.

Start by targeting adequate protein intake to support muscle maintenance and repair. Both plant and animal sources are appropriate, including poultry, fish, eggs, tofu, and legumes. Next, target healthy fats from sources like avocados, nuts, seeds, olive oil, and fatty fish. These provide essential fatty acids and promote satiety. Finally, choose minimally processed carbohydrates such as whole grains, vegetables, and legumes for sustained energy and fiber intake.

Once you achieve a sustainable balance, adjust your macronutrient ratios based on individual preferences and goals, such as higher protein intake for muscle building or more fats for ketogenic intermittent-fasting approaches. Regular monitoring and adjustments based on progress and overall well-being are essential. Consult with a registered dietitian or nutritionist if you have underlying health conditions or feel you could benefit from personalized guidance.

Calculating Your Basic Caloric Needs

Calculating macros while practicing intermittent fasting involves determining your daily caloric needs and then allocating percentages (or specific amounts of calories, if you prefer) to each macronutrient: protein, carbohydrates, and fats.

Here’s a general process:

  1. Determine your total daily energy expenditure (TDEE) using an online calculator or formula based on factors like age, gender, weight, height, and activity level. This will be your maintenance caloric intake. If you’re aiming to lose or gain weight, you will need to subtract or add a couple hundred calories to this number in order to create a calorie deficit or surplus. 
  2. Decide on your macronutrient distribution based on your goals and preferences. While this distribution can vary, an example of a balanced approach to macros might look something like this:
    • Protein: 25–35% of total calories
    • Carbohydrates: 30–50% of total calories
    • Fats: 25–35% of total calories
  3. Convert these percentages into grams by multiplying them by the TDEE you calculated in step 1. For example, if your TDEE is 2,000 calories and you want to aim for 30% protein intake, you would calculate 2,000 × 0.30 = 600 calories from protein. If you want to portion your macros by weight, divide the calorie amounts by the calories-per-gram of each macronutrient: 4 calories per gram for protein and carbohydrates, and 9 calories per gram for fats. In our example, you’d divide the protein calories by 4 calories per gram: 600 ÷ 4 = 150 grams of protein.
  4. Adjust the macros to fit your eating window during intermittent fasting. You may distribute your macros evenly across your eating window or adjust the timing of certain macros based on your preferences and energy needs before and after workouts.
  5. Monitor your progress and adjust your macros based on how you feel and the progress you’re seeing towards your health and fitness goals, and consult with a registered dietitian for personalized guidance.

Understanding the Role of Macros in Intermittent Fasting

If you’re someone who practices intermittent fasting, macros are important because they ensure that your body receives the necessary nutrients for optimal health, energy, and performance during eating windows.

Protein supports muscle repair and growth, which is crucial for maintaining lean body mass, especially if you’re exercising while fasting.

Carbohydrates provide energy for workouts and to sustain overall energy levels, while also providing a source of fiber that will contribute to feelings of satiety. Carb quality is very important here if fat burning is your goal. At the start and end of your fast, you will want to avoid highly processed carbohydrates and added sugars because they can spike your blood sugar and insulin, thus reducing the fat-burning benefits that fasting provides. Instead choose high-fiber, minimally processed carbohydrates, such as non-starchy vegetables, nuts, dairy, and legumes. Fats play a role in hormone production, satiety, and absorption of fat-soluble vitamins. Healthy fats provide a source of energy that does not spike your blood sugar, meaning insulin levels remain low, which can increase your chances of fat burning and weight loss.

Balancing macros appropriately can help ensure that you meet your nutritional needs, support your fitness goals, and maintain overall well-being while practicing intermittent fasting.

Tracking and Adjusting Your Macros

Once you start tracking your macros regularly, you can feel free to adjust them depending on your health goals. If your goal is weight loss, focus on protein first in order to minimize the amount of weight loss coming from loss of muscle mass. A higher protein intake of about 1.6–2.2 g/kg of body weight tends to be a good place to start. Your carbohydrates and fat intake will make up the remaining calories. As long as you are generally healthy, the distribution of carbohydrates and fats should not matter as much.

A landmark study published in the Journal of the American Medical Association (JAMA) found that weight loss was equivalent in the low-fat and low-carbohydrate groups as long as diet quality was high — meaning if your carbohydrates and fats are coming from minimally processed foods high in fiber and micronutrients and low in added sugars and processed oils, you should see similar weight-loss results. Therefore, what percentage of your diet comes from carbohydrates and what percentage comes from healthy fats is up to your personal preference and what you feel best consuming. 

Of note, those with diabetes, heart disease, and other conditions may need to have a more directed approach to their protein, carbohydrate, and/or fat distribution. If you fall within these categories, it is best to work with a registered dietitian or your healthcare provider to determine what ratio is best for your unique condition.

Pay attention to portion sizes and ensure you stay within your macros targets for carbohydrates, protein, and fats. Monitor your progress regularly, and adjust your macros based on how your body responds. If you’re not seeing results, consider adjusting your calorie intake or macros ratios slightly. Be patient and make gradual changes to avoid drastic swings in diet. Aim for consistency as you stick to your macros targets, eat nutrient-dense foods, and prioritize regular exercise to support your goals.

The Impact of Exercise on Intermittent-Fasting Ratios

If you work out regularly, your macros may need some adjustments to support your increased energy expenditure and muscle repair and recovery.

Here’s one way to tweak your macros:

  • Protein: Increase your protein intake to help your muscles — which you broke down during exercise — to repair and grow. Aim to consume 1.6–2.2 g/kg of body weight per day, depending on the intensity and frequency of your workouts.
  • Carbohydrates: Your carbohydrate intake will fluctuate based on the type of exercise you are doing. Higher-intensity workouts, such as HIIT training or heavy weight lifting, are more dependent on carbohydrates for fuel, whereas lower-intensity exercise, such as walking or a mellow bike ride, uses more fat, so less carbohydrates are needed. No matter the quantity of carbs you consume, aim for minimally processed sources like whole grains, legumes, fruits, and vegetables.
  • Fats: Maintain a moderate intake of healthy fats to support hormone production, satiety, and overall health. Fat is also a great fuel source for low-to-moderate exercise. Include sources like avocados, nuts, seeds, and fatty fish.

Adjust your macros based on your specific fitness goals, workout intensity, and individual response to different macronutrient ratios. Experiment with different ratios and monitor how your body feels and performs to find the optimal balance for your needs. Consulting with a registered dietitian or nutritionist can provide personalized guidance based on your goals and lifestyle.

Is Tracking Macros Really Necessary?

Tracking macros is not strictly necessary to lose weight and gain health (and you definitely don’t need to count calories!), but it can be beneficial if you have specific fitness goals, such as muscle gain, fat loss, or improved athletic performance. Paying attention to your macros helps you consume the right balance of protein, carbohydrates, and fats to support your goals and meet your nutritional needs, especially when you condense the amount of time you’ll be eating each day by intermittent fasting. Tracking macros can also provide valuable insights into your dietary habits, portion sizes, and nutrient intake, which can be useful information if you’re starting a new health journey.

However, tracking macros isn’t for everyone. Some people may find it tedious or stressful, while others may have success with intuitive eating, following general dietary guidelines, or plating methods. Ultimately, whether or not you choose to track macros depends on your individual preferences, goals, and lifestyle. If you’re unsure, consulting with a registered dietitian or nutritionist can help you determine the best approach for your needs.

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Nicole Grant, RD
Posted in Health & Science

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