The studies seem to suggest that intermittent fasting can result in similar weight loss and fat loss to continuous dieting. Muscle is preserved with Intermittent fasting, especially with high-protein. Intermittent fasting may not be optimal for increasing lean muscle mass.
HOW TO INTERMITTENT FAST WITHOUT LOSING MUSCLE OVERVIEW
- How to intermittent fast without muscle loss is a frequently asked question.
- An intermittent fasting protein shake can help preserve muscle while intermittent fasting. Most researchers recommend resistance exercise and a protein intake of .8 grams or higher per pound.
- Intermittent fasting muscle loss does not have to occur if your protein intake is high.
- Intermittent fasting may not be optimal for increasing lean muscle mass.
RESEARCH UPDATE: INTERMITTENT FASTING TO LOSE FAT: MECHANISMS OF TIME-RESTRICTED EATING WEIGHT LOSS UNCOVERED
Previously written, intermittent fasting discussed that time-restricted eating and calorie-controlled diets have similar weight loss when calories are similar. There are many different fasting protocols, such as intermittent fasting, skip breakfast or dinner, and 16/8 intermittent fasting morning workout (Fast for 16 hours and feed for 8). Check out the intermittent fasting calculator to help you structure your efforts.
A new study has unraveled a new twist: time-restricted eating can contribute to weight loss. Most studies on time-restricted feeding have used apps and other food-tracking devices, which need to be more accurate. Researchers took subjects and placed them in a metabolic chamber for 3 days. When you are in a metabolic chamber, everything gets accurately measured.
Calories, exercise, sleep cycle, and metabolism are tightly monitored. The subjects switched from a regular diet to a time-restricted feeding diet to reduce inaccuracies. The regular diet consisted of an 11-hour eating window, and the time-restricted feeding group had a 5.5-hour feeding window. The time-restricted feeding group ate between 8 am and 1:30 pm.
Both groups ate the same calories: ~1800 kcals, 261 g carbohydrate, 57g fat, and 60 g protein. There were no differences between groups in 24-hour energy expenditure, basal metabolic rate, or sleeping metabolic rate. There were also no differences in non-exercise activity thermogenesis or exercise activity thermogenesis.
Ready for the shocker? The time-restricted feeding group had a 22.7% increase in fecal energy loss and a trend of increasing 14.5% in urine energy compared to the normal diet group.
The authors explain why the time-restricted feeding group was losing more calories thru waste such as feces and urine; it could be because of the larger amount of calories being consumed in a short time compared to having meals throughout the day. ”
The authors found that in one day, fecal and urine output changes by ~40 kcal, which, if held constant, would result in a roughly 280 kcal deficit per week by simply altering the timing of food intake. The author suggests that time-restricted feeding could induce negative energy balance by increasing fecal and urine energy excretion.
This seemingly negligible energy excretion elevation can explain up to 64.3% – 72.2% of weight loss in previous studies. More studies need to be conducted to unravel this mechanism, but this was the first to show increased fecal and urine energy loss with time-restricted feeding.(14)
HOW TO PREVENT MUSCLE LOSS DURING INTERMITTENT FASTING
Intermittent fasting has been advocated to be superior to conventional diets for boosting lean muscle mass and superior fat loss because of higher increases in GH and other metabolic benefits. The pros and cons of intermittent fasting are increased parameters of immune function and weight loss; downfalls include such as reduced anabolic hormones (i.e., decreased testosterone and IGF-1).(1) There are several forms of fasting: Alternate Day Fasting (i.e., eating every other day), Whole Day Fasting (i.e., fasting for 24 hours), and Time-Restricted Feeding (i.e., fasting for several hours at a time).
The most popular method of intermittent fasting to positively change weight and fat loss is 16 hours. Ramadan is the most widely accepted religious reason for fasting for Muslims, in which one does not eat from sunrise to sunset. During Ramadan, Muslims fast for 12-18 hours a day and do this for 30 days. During Ramadan, food and liquid are only eaten at night.
A recent meta-analysis of Ramadan and non-Ramadan intermittent fasting found that fasting can result in small decreases in fat and body weight. Still, the effect of these changes was mediated by the % body fat of the person starting the diet. Those with more body fat lost more weight and body fat during Ramadan than those with less body fat.
DOES FASTING CAUSE MUSCLE LOSS?
The other interesting finding from the study was that Ramadan was not associated with the loss of lean muscle.(2) Research suggests a positive calorie intake is needed for muscle growth. Since fasting consists of long periods without protein, it was suggested that long-term fasting muscle loss occurs. Intermittent fasting and muscle loss were a no-brainer!
However, the study found that this was another fasting muscle loss myth. Other common myths are related to hunger control. In a meta-analysis of intermittent fasting, some of the most common myths regarding fasting were debunked. The results were:
a.) One would suspect that fasting for 16 hours would result in low adherence and high dropout rates; however, intermittent fasting has similar dropout rates to traditional low-calorie dieting.
b.) Intermittent fasting is safe and improves glycemia, although there is a potential for hypoglycemia that has been documented.
c.) Hunger levels remain stable or generally decrease.(3)
Several large-scale literature reviews have found that intermittent fasting is similar to calorie restriction; both equally reduced body weight, body fat, and changes in lean mass.(4-6) There is no “metabolic advantage” to intermittent fasting, as you commonly hear referred to by social media fitness influencers. Intermittent fasting is thus an alternative to calorie-restricted diets, but the outcomes are very similar for body composition (i.e., fat loss, weight loss, lean mass).
The benefit of intermittent fasting is that it eliminates calorie counting throughout the day. Studies have shown that intermittent fasting with food restriction lasting 12-24 hours lose weight without counting calories.(7) Thus, intermittent may be an easy way to create a caloric deficit compared to a continuous diet in which calories must be meticulously calculated for the day.
CAN YOU BUILD MUSCLE WHILE FASTING?
Intermittent fasting has been suggested to be great for losing fat but not for building lean muscle mass. a common thread by many bodybuilders is, “Do you lose muscle while fasting?” Check out the intermittent fasting muscle loss Reddit thread.
A 2019 study by Tinsley et al. had the intermittent fasting community saying, “See, I told you so…you can gain muscle while fasting,” when he found that intermittent fasting produced similar increases in lean mass as a conventional diet. This study found that prolonged fasting and muscle loss do not have to occur if you follow the right diet.