Intermittent Fasting: Part 2

What & how much to eat

Intermittent Fasting: Part 2 - What & how much to eat
A few weeks ago, I wrote an article all about Intermittent Fasting: What It Is and How To Do It. (If you didn’t get a chance to read it, you may want to give it a quick look.)

The article inspired much conversation, so I thought a “Part 2” was in order. Today, I will answers the questions I received from you: “What should I be eating on a day that I do an Intermittent Fast?” and “How do you know if you are eating enough on those days?”


The biggest misconception about IF is that you will be consuming fewer calories than if you were eating consistently throughout the day. This is not the case. You are just adjusting WHEN you consume your calories.

As a reminder, the 16/8 Intermittent Fast (IF) Method has you fasting for 16 hours (including your sleeping hours) and then eating for 8 hours during the day. (For many people, the 11am to 7pm eating window works great, but you can always adjust an hour in either direction if needed.)

During your eight eating hours, you will consume whatever your daily caloric needs may be. Now, I don’t believe that you need to obsessively count calories and macronutrient (protein, carbs, fat) grams to be successful with IF, or any nutritional program for that matter. However, it would be crazy to say that you NEVER have to track them either. The goal is to become educated about food so that you can quickly eyeball a portion and understand that even if it is a bit above your daily totals, you will still be okay.

With that said, I like to give my clients a starting place so they have some rough nutritional targets. The following sections explain how to determine your needed daily calories and macronutrient targets.


To find your needed daily calorie intake, you must first determine your lean body mass (LBM). To do this, you need to find out your body fat percentage. Once you know your percentage, simply take that number and multiply it by your weight. That will give you your pounds of fat. Subtract the pounds of fat from your total weight and you have your LBM.

For example:
140 pound woman with 19% body fat
140 x .19 = 26.6 pounds of body fat

She has 26.6 pounds of body fat. Subtract that number from 140, and you get 113.4 lbs. That’s her LBM.


Now, to figure out your needed daily calories, you want to multiply your LBM by your base number. The base number is dependent on your body fat percentage. If you or your client is just starting out, daily calories will be a bit lower, because there is more body fat to lose. If you are advanced or someone who is lifting heavy and hard, calories will be higher to support more muscle tissue. Based on this, use the following information to determine your base number:

For beginners or people over 23% body fat, multiply your LBM by 11.

For anyone between 20-22% body fat, multiply your LBM by 12.

Anyone below 20% should multiply that number by 13 or 14.

For the example above, take the 113.4 pounds of LBM and multiply it by 13 (since her body fat was 19%). This equals 1,474.2,

Thus, that woman should be taking in around 1470 calories each day. You can increase this by 100 on training days, and you can then even decrease it by 100 on non-training days.


Protein. Simply take that LBM number and multiply it by 1 to determine how many grams of protein to eat each day. That may seem like a lot for some women, but if you are in the gym training hard, you need it.

Carbohydrates. On non-training days, keep your carbohydrates low (approximately 50-75 grams). That said, all vegetables are “free,” so eat those with each meal. On training days, you will need more carbohydrates. Multiply your LBM by .75 – 1 to determine an approximate number of carbohydrates. The woman in our example would eat approximately 85 – 113 grams of carbs. Since her body fat is low, she should target a higher point on the range.

Fat. Once you’ve determined your carbs and protein for the day, you are left with fat to make up the rest of the calories. To determine the approximate number of fat grams you should have, determine how many calories you have left (after protein and carbs) and divide the by 9 (the number of calories in a gram of fat). Since you are eating higher carbs on the days that you train, your fat intake will be a bit lower. On the days you don’t train, focus more on protein and healthy fats throughout the day.

Once you have these baseline numbers, then you can easily create your eating plan. However, DO NOT become married to the numbers. This is only a guide and to help you get started, because IF can be a little different approach for many people.


Here is a sample meal plan if you are doing an Intermittent Fast & training in the evening.

Note: This is just an example and may not fulfill YOUR caloric needs.

11am- Meal #1
3 whole eggs, cooked with spinach and peppers, 1/2 avocado

3pm- Snack
1 scoop whey protein mixed with water

5pm- Train

6pm- Post Workout Shake
1 cup unsweetened almond milk, 1 scoop chocolate whey protein, 1 small banana, 1/2 cup frozen blueberries, 1 tablespoon cacao

7pm Meal #2- Dinner
6 ounce salmon filet, steamed and seasoned broccoli, 2 small boiled red potatoes, 1/2 cup mixed nuts, 1 square dark chocolate

Important Notes
1. You can tailor this to fit the hours that work for you. However, if you train at night, reserve your carbs for your post workout shake and a dinner.

2. Remember, keep those numbers in your mind only to create the right portions, don’t make yourself crazy counting calories.

3. In the morning, you’ll want to have 1-2 cups of black coffee and a serving of BCAA’s, which can help with hunger as you get used to the process. Make sure to drink 80-90 ounces of water each day.

Next week, I’ll be back with an article covering how to eat on your morning training days.

Callie Durbrow

Callie Durbrow is the owner of Durbrow Performance Training and the author of Strong and Sexy in 25 Minutes.

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