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Building Muscle While Intermittent Fasting

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How much are you willing to sacrifice to achieve your fitness goals? Browsing through fad diets and trendy training programs could be one way to adopt an health-optimized lifestyle, but if you’re a body builder who has already realized your preliminary wellness goal and want to take your physique to the next level, then you may want to consider adding one more factor to your fitness formula.

What if instead of abstaining from carbohydrates, meats or dairy, you actually gave up time? Intermittent Fasting1 (IF) is a dietary routine where practitioners only eat during designated times and forgo consuming calories outside of those “feeding windows.”

MORE: Here’s What Intermittent Fasting Does for Your Sex Drive

The UMZU blog has written extensively about the pros and cons of various intermittent fasting protocols, how to begin an IF program and popular supplements fasters regularly use. But one of the main features of IF is that there are no limits to what foods you can eat, only when you can eat.

The goal of intermittent fasting is to have regulated “feeding patterns” so that your body has time to metabolize the nutrients and enhance cell responsiveness. As your body adapts to cycles of eating and non-eating, the focus therefore becomes about the time of day of your calorie intake rather than which foods to eat.

Top Three Intermittent Fasting Schedules

Typically, there are three main strands of fasting that people use to take advantage of IF benefits: the 16/8, the 24 hour, and the 5:2 schedule.

16:8 Intermittent Fasting

The most common variant of IF is the 16/8 approach. The 16 hour intermittent fast is highly favored for its simplicity. Fasting for 16 hours and eating during an 8 hour window. You are encouraged to skip breakfast everyday and eat around 12-8 pm, tailoring the times to fit your routine.

The Eat-Stop-Eat Diet (24-Hour Fasting)

The 24 hour schedule is pretty self explanatory. You fast for 24 hours once or twice a week, However this method is not necessarily the best option for weight loss and muscle growth.

5:2 Intermittent Fasting

The 5:2 schedule is also pretty straight forward. For two days during the week you commit to eating 500 calories each day, and eat normally the other 5 days. One thing to keep in mind is, the two days should not be consecutive though. For example, fasting Mondays and Fridays. This method doesn’t necessarily give you the best results for weight loss.

An image of a fit couple posing for selfies

Dietary routines like the Thermo Diet have been proven to burn fat and encourage muscle growth.

Benefits of Intermittent Fasting for Muscle Growth

One study showed that participants who ate the same amount of calories as before, but just consumed one big meal in the evening, actually lost body fat which supports muscle growth3

More research still needs to be done to study the full benefits of IF for muscle growth. Based on the current findings, we know that when meal frequency is decreased without a large reduction in overall calorie intake, there could be positive side effects on the body’s composition, specifically in lean mass.  

So how do you gain muscle during IF?  If you are working out while fasting, you are more likely to burn more fat and sustain muscle. This goes back to insulin sensitivity. The fewer calories you eat, the more fat burning. This means that the food you are consuming is being distributed to where it needs to be. Waiting during that period of time after you have eaten is considered your “fasting window”. After you have eaten, your body needs that energy and will consume it right away rather than store it for later. This is good news for people who are trying to limit their fat gain during muscle conditioning.

Fasting is considered one of the most intimidating plans to follow, but it doesn’t have to be scary. It’s important to remember that the quality of the food is always an important variable for weight loss and muscle growth. Regardless of which schedule you prefer, remember, it might take your body some time (about a week) to adjust to the new routine.

An image of a man lifting weights.

Many bodybuilders turn to natural supplements to assist with muscle growth.

Tips for Building Muscle While Intermittent Fasting

Here are a few proven strategies for lean bulking (building muscle while dropping fat).

1. Don’t Be Afraid to Eat More Fat

A lean bulk phase means you have to eat more. Often, this entails a calorie intake of 3,000-4,000 calories. For those trying to gain muscle for the first time, they may not be accustomed to eating that much. Intermittent fasting may make the process more difficult since you have a smaller window for eating. This means you have to eat larger portion meals, sometimes as high as 1,500 calories in one sitting.

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To increase calories, don’t be afraid to consume more fat. There seems to be this idea that fats have to be kept to a minimum during a lean bulk. Supposedly, if you eat fat, you get fat since fat is the most easily stored macronutrient in the body. Remember, though, that it all comes down to a calorie surplus. If you eat more than your body needs to put on muscle, you’re going to put on fat whether the calories primarily come from fat, carbs or protein.

Go ahead and add an avocado to your meal or eat grass-fed beef that’s high in saturated fat. We recommend keeping the fat to about 30-35 percent of your total caloric intake during a lean bulk.

2. Don’t Obsess About Always Eating Clean

Forget about limiting your meals to chicken breasts, white rice, and bland potatoes. We’re not undermining the importance of sticking to hormone-free meats, whole fruits, and healthy carb sources. However, allow yourself to indulge by having foods that would normally be limited to a once-a-week cheat day.
This is certainly one of our favorite fasting tips because it’s not ultra-restrictive. It’s absolutely acceptable to enjoy a sugary indulgence at a birthday party, or have a drink at a social outing.

3. Don’t Obsess About Meal Timing

Some people think they can only eat in accordance with their adopted intermittent fasting protocol. This doesn’t always sense for weightlifters who are on a lean bulk. You should absolutely consume smaller snacks outside your regular lunch and dinner. This doesn’t even have to be a conventional meal. Nosh on fresh fruit, collagen smoothies or bone broth. In fact, collagen and bone broth are amazing nutrient sources during a lean bulk.

Can Intermittent Fasting Promote Muscle Growth?

Just changing the timing of your meals can actually promote weight loss. Eating during a restricted time of day means eating fewer calories, which translates into weight loss. In most cases, you will be taking in fewer calories unless you overcompensate during your feeding window, which in essence is counterproductive.

When our body abstains from food for a period of time, it turns to stored fat, or energy retained from calories previously consumed. Our body adapts pretty quickly to make the stored energy more accessible, and insulin is directly affected. When we eat our insulin levels increase, however, when we fast our levels become lower which facilitate fat burning. Abstaining from too many calories increases insulin sensitivity which enhances overall cell responsiveness.

An image of a fit woman doing a yoga pose.

Does Intermittent Fasting Promote Muscle Loss?

At first glance, it doesn’t seem that IF and muscle gain can coexist. The truth is, you can participate in intermittent fasting without compromising your strengthening goals. It’s recommended to shorten your fasting period to about 10-12 hours daily to ensure you are getting adequate nutrient consumption. Making the most of your caloric intake is imperative if you want to decrease fat mass and increase lean mass. Keep this in mind when you are planning your routine. 

TODAY: How to Successfully Start Intermittent Fasting 

There is some evidence that supports how intermittent fasting may help you hold on to muscle mass when dieting2. These findings determined that there are some benefits to maintaining muscle mass while losing weight during IF.

Citations and Sources

Tinsley GM, Butler NK, Forsse JS, et al. Intermittent fasting combined with resistance training: effects on body composition, muscular performance, and dietary intake. J Int Soc Sports Nutr. 2015;12(S1). doi:10.1186/1550-2783-12-s1-p38
Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obesity Reviews. 2011;12(7):e593-e601. doi:10.1111/j.1467-789x.2011.00873.x
Stote KS, Baer DJ, Spears K, et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. The American Journal of Clinical Nutrition. 2007;85(4):981-988. doi:10.1093/ajcn/85.4.981

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Trey Triplette

Trey is a Certified Nutritionist, AADE Diabetes Coach and owner of 3natural Bionutrition. A former Division I college athlete who played football for the Louisiana State University Tigers staying in shape and optimizing nutrition performance is nothing new to him. 3natural Bionutrition provides a wide range of all-natural solutions for all types of dietary restrictions, eating habits and health-related goals to optimize your performance, recovery, training, health and quality of life. Trey received his training from San Francisco College where he studied a myriad of nutritional aspects including but not limited to clinical nutrition, food service, food science, and nutritional biochemistry. While attaining his certification he took part in many nutritional research studies and projects and community organizations and nutritional health centers such as the Children’s Council of San Francisco. He also actively supports the San Diego Ag in the Classroom, Oceanside Chamber of Commerce, Camp Pendleton Armed Services, Triathlon Club of San Diego and Alpha Bridge Partners to name a few.
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