Intermittent fasting (IF) has been in the spotlight for a few years. These diets are often touted to improve health, facilitate weight loss, and encourage a healthy aging process.
However, as with all diets, we need to look at the scientific evidence to see if IF is really helpful for a healthy lifestyle.
What is intermittent fasting? This affect seasonal periods of dieting and eating.
There are different types of FIs. These often focus more on when you eat than on what you eat. However, some versions of IF also specify certain dietary or calorie restrictions within the feeding window.
Common types of IFs include:
Time-restricted feeding (TRF):
This involves limiting your intake to a daily “feeding window” each day. The most common example is the 16:8 diet – which includes an 8-hour diet and a 16-hour fast. Other variations include limiting your consumption to a 4 to 12 hour consumption period. The timing of the eating space can also vary, that is,. early or late TRF.
Alternating Day Fasting (ADF):
This involves fasting a few days a week. For example, with the 5:2 diet, you consume 600 fewer calories 2 days a week and consume your normal intake on the remaining 5 days of the week. The 6:1 diet (also known as “restless eating”) is similar but typically includes fasting 24 hours a day per week and eating normally for the remaining 6 days.
Mimic Diet (FMD): This diet is low in carbohydrates and protein, but high in unsaturated fats, and typically contains only one-third to one-half of a person’s normal calories.
Since IF often leads to a reduction in calorie intake, it can lead to short-term weight loss.
However, some studies have shown that IF leads to similar weight loss results as a “traditional” calorie-controlled balanced diet. For example, a systematic review in 2020 found that an interval diet resulted in weight loss between 0.8% and 13.0%, similar to a conventional calorie-restricted diet (1).
Some loss of muscle mass and improved blood sugar control were also observed. It should be noted that most of the studies in this area are small and of short duration.
When discussing dietary approaches and related weight loss, it is important to consider long-term sustainability for maintaining weight loss. Current evidence suggests that it is really difficult for people with large bodies to lose and maintain weight, and that it is common to regain weight within a few years (2, 3, 4).
Cycles of losing and regaining weight are also quite common, and this has been linked to their own health problems (4). Therefore, for many people focused on weight loss, the IM approach may not be practical or helpful, especially if they have a messy relationship with food or their bodies.
Impact on heart health
There are mixed results about the impact of IF on heart disease risk.
Ramadan fasting data show lower cholesterol and blood pressure in healthy study participants (5). These data also identified an increase in heart problems during the “fast-breaking” period compared with the non-fasting days; but further research is needed.
different studies have establish similar reductions in blood pressure and enhancement in cholesterol from IF(6)
. However, some studies have found a reduction in “good” HDL cholesterol and mixed results on LDL cholesterol (6). Several factors can contribute to this, including fast time and its connection to our biological clock.
bouncing breakfast is connect with an increase risk of death from heart disorder and all causes (7). Although IF may have a positive effect on cardiovascular health, there are conflicting results and ongoing research is still needed to investigate this.
Impact on diabetes risk
An interesting study from 2018 investigate the effects of early TRF (9am-3pm diet versus 12-hour eating time) on men Women at high risk for diabetes show a reduction in diabetes risk that was not related to weight loss (9).
This includes: improved insulin sensitivity, improved pancreatic function, and reduced blood pressure. This provides evidence that synchronizing IF time with participants’ body clocks, by eating more early in the day, may play an important role.
Similarly, skipping breakfast is associate with an increase risk of diabetes and poorer blood sugar control (10, 11).
IF shows promise when it comes to reducing the risk of type 2 diabetes, and early TRF may be particularly beneficial. However, as in all areas of IF research, longer and ongoing human trials are need.
Research in mice has shown that foot-and-mouth disease is associate with rebuilding the gut microbiome and ameliorating inflammatory bowel disease (IBD) (12, 13).
In humans, fasting Ramadan is associate with a positive improvement of the gut microbiota (14). However, this has been observe to return to baseline once the brisk is stop.
While some exciting research is emerging in this area, we now have more research supporting the gut health benefits of a varied diet, especially a variety of Sprig foods rich in nutrients. fiber from fruits and vegetables as well as foods containing whole grains (15, 16, 17).
Are there any risks with intermittent fasting? Fasting for 24 hours or more is associate with serious health complications, including kidney and heart problems and possibly death (18,19).
IF is generally less dangerous than prolonged fasting, but there are still significant risks to consider. For example, IF can be harmful for people who need a steady supply of energy and nutrients. For example: people who are unwell, eat less, pregnant women or young children.
Long-term fasting may not be appropriate for people with diabetes who are at risk for low blood sugar. Especially for those who are taking insulin or certain diabetes medications. There may also a risk of hyperglycemia (high blood sugar) if large amounts of food are consume after fasting, which is not uncommon with extreme hunger.
Many athletes and regular exercisers also need regular nutritional supplements to optimize training results. IF associated with decreased muscle mass; although there have mixed results on this (20, 21).
IF can negatively affect immunity by reducing the number of white blood cells that play an important role in our immune response (22).
Another consideration was that the risk of gallstones nearly doubled in women. Who fasted for 14 hours compared with those who fasted for 8 hours overnight (23).
It is important to emphasize that fasting, including SI, can be a trigger, symptom, or sign of a socially accepted eating disorder.
Therefore, any type of fasting, including IF. It is not safe or appropriate for anyone recovering from an eating disorder or eating disorder. Fasting has also shown to be a predictor of eating disorders, including binge eating disorder, bulimia, and purging disorder (24,25,26).
For some people, fasting can also lead to unpleasant side effects such as (27, 28,29):
- Irritability and moodiness
- Poor sleep
- Decreased energy levels
- Be less sedentary
It is important to note that the effects of fasting are unknown in different groups. Therefore, further human research is need.
IF continues to be a hugely popular diet and has some interesting and promising research related to heart health and diabetes risk.
Research involving early restrictive eating and the effects of our circadian clock appears to be particularly positive. However, there are significant risks associated with fasting, including IF, so this is not the right approach for many people.
There is still much we don’t know about the long-term effects of IF. On humans and on people with various medical conditions. You should seek advice from licensed healthcare professionals. If you are considering making a major change to your diet like this.