Intermittent fasting or time-restricted feeding is when you have set fasting and eating windows. While some people think this is a new strategy, everyone does some type of fasting since you fast during sleep.
According to a study from the Journal Cell Metabolism called Fasting Blood Glucose as a Predictor of Mortality Lost in Translation, higher glucose levels in humans seem to be associated with higher mortality rates. One of the possible benefits of fasting is that it can help reduce blood glucose levels, decreasing mortality.
It seems that time-restricted feeding can have a positive effect on fat burning when on a caloric restriction by increasing hepatic lipase. In other words, it increases the enzyme metabolizing fat for energy production.
Since digestion is an active process, it requires energy to digest, absorb, and use the nutrients you eat. This process involves certain functions that, if ongoing throughout a 24-hour cycle, can increase the expression of certain pro-inflammatory markers. So, time-restricted feeding seems to give the liver a break, improving its function and health.
Additionally, it might increase brown fat, increasing the body’s thermogenesis (fat-burning properties) and decreasing the risk of non-alcoholic fatty liver disease.
There are several benefits of time-restricted feeding on gut health. It seems to impact mucosal lining positively, it helps reduce Lacto Bacillus (in high levels can be correlated to different metabolic disorders), and it might increase the formation of good bacteria in the gut to promote overall gut health.
It seems that a 6-8 hour feeding window has a positive effect on health. Benefits can include improved insulin sensitivity, decreased blood pressure, reduced oxidative stress, and reduction in hunger levels during the evening.
While an eating window of 4-6 hours might benefit some people, others might see a weight increase, hormonal changes, and difficulty with adherence.
The best scenario would be to start eating around 10 am to 12 pm and stop eating at 6 pm to 8 pm. This will get the most out of time-restricted eating but still be able to follow social norms. Such activities might include time with family, eating lunch with others, and eating at a reasonable hour.
Now, remember that everyone is different. Make sure to adjust the feeding window based on your current needs and lifestyle. The best outcome people have regarding fasting is when they can stick to the schedule instead of switching it around every day.
To shift your eating window, you need time for the transition. Allow yourself a transition time from one week to ten days, where you shift your eating window by one hour each day. Once you establish a feeding window that is comfortable for you (and you can maintain over time), keep it going for at least 30 days.
Unfortunately, there is no black-and-white answer to this question. To determine if a food breaks a fast relies on its effect on glucose levels. Glucose levels are the ultimate test of whether you are in a fed or fasted state. To know if you have broken a fast with precision, you would need to use a continuous glucose monitor.
However, there are some things that research shows won’t break a fast:
So, what breaks a fast? Carbs, especially simple sugars (even one gram of sugar can disrupt a fasted state), can break a fast.
Since fats don’t have a large effect on blood glucose levels, and protein has a moderate effect, they might potentially not break a fast. But, what breaks a fast depends on every person’s sugar levels. For example, some people might be able to eat a handful of peanuts (fats) without affecting glucose levels (not breaking a fast). But, if your blood glucose levels are constantly high, even one peanut might result in breaking a fast.
This means that breaking a fast is very contextual (depends on what was the last thing you ate, at what time, the quantity, and any activity levels you had).
According to research, it does appear that muscle tissue is better able to undergo hypertrophy by enhanced protein synthesis early in the day due to the expression of a gene called BMAL.
This gene helps regulate different protein synthesis pathways within muscle cells. For that reason, it seems that eating protein early in the day supports muscle tissue maintenance and growth.
Now, it doesn’t matter if you are training early in the morning or late at night. The only thing that matters is consuming protein first thing in the morning to favor hypertrophy.
Currently, the data regarding sugar-free sweeteners is still mixed. There is evidence that when people ingest artificial sweeteners, it can create a temporary increase in blood glucose followed by a temporary blood glucose decrease.
It seems that in moderation, plant-based options (stevia) have a minimal impact on blood glucose levels.
While aspartame and sucralose might not increase blood glucose levels, there is some evidence that when consumed in large quantities, it might have a negative effect on the gut microbiome.
So, do artificial sweeteners break a fast? It depends on the amount, the type, and how frequently you add them. Adding one once in a while is okay as long as you don’t overindulge on them.
