Major points
- Intermittent energy restriction involves alternating between periods where normal eating is allowed and fasting periods, which leads to a reduced overall calorie intake.
- There are two main types of intermittent energy restriction: intermittent fasting (IMF), where fasting occurs on whole days, and time-restricted eating (TRE), where daily eating times are significantly limited.
- There is currently no convincing evidence that intermittent energy restriction offers better health effects compared to regular diets. However, intermittent energy restriction can certainly be combined with Neatic.
What is intermittent energy restriction?
The term “intermittent energy restriction” is self-explanatory. “Intermittent” refers to a time period, and “energy restriction” means eating nothing or significantly less than usual. Therefore, “intermittent energy restriction” means eating nothing or significantly less within a defined period of time. This results in a reduced total calorie intake.
Intermittent energy restriction corresponds to weight-loss strategy 3. If you want to learn more about the other weight-loss strategies, click here.
Is intermittent energy restriction always the same?
No! There are two main types, each with different subtypes: intermittent fasting and time-restricted eating.
1.Intermittent fasting (= IMF)
This form involves fasting for entire days. The following subtypes are particularly popular:
- 5:2 fasting: You eat normally for five days a week and fast for two days. For example, you might fast completely on Tuesdays and Fridays, while eating normally on the other five days. Sometimes, fasting days do not mean total abstinence from food, but allow up to 500 kilocalories, which could be the equivalent of two cheese rolls or half a frozen pizza.
- 1:1 fasting: Days of normal eating alternate with fasting days. For example, you would eat normally on Monday, Wednesday, Friday, and Sunday, while fasting on Tuesday, Thursday, Saturday, and the next Monday. In the modified version, you would not completely refrain from food, but limit your calorie intake to around 500 kilocalories on fasting days.
- Periodic fasting: Fasting lasts for more than one consecutive day. For example, you might fast for a whole week or severely restrict your calorie intake during this period. This type of fasting is also common in certain religious practices.
2. Time-restricted eating (TRE)
In this type, you eat every day, but the eating period is limited. The most popular form is 16:8 fasting, where you fast for 16 hours a day and can eat during an 8-hour window. Depending on when you start eating, there are two types of 16:8 fasting:
- Early TRE (eTRE): You start eating early, for example at 8 a.m., and can eat until 4 p.m. From 4 p.m. until the next day at 8 a.m. you fast.
- Midday TRE (mTRE): You start eating around noon, and can eat until 8 p.m.. From 8 p.m. until noon the next day, you fast.
There are more extreme versions, such as 20:4 fasting, where you fast for 20 hours and eat during a 4-hour window. However, these extreme methods are difficult for most people to maintain.
Why do people practice intermittent energy restrictions and what does research say?
It is often claimed that intermittent energy restriction helps shed pounds, improves metabolism, prevents cardiovascular diseases, reduces inflammation, boosts fitness, and extends life. However, many of these claims are either unproven or insufficiently supported by scientific studies.
When studies do exist, they often suffer from several common issues:
- The number of participants is too small, making the results less reliable.
- The follow-up period is too short to assess the risk of the yo-yo effect.
- A high dropout rate, where participants who struggled with fasting may have left the study, potentially skewing the results.
- Different types of intermittent fasting are studied, making comparisons between studies difficult.
- Often, there is no control group with a standard diet, so it is unclear how intermittent fasting compares to regular dieting.
- Conflicts of interest may exist, as some studies investigate products being marketed for sale.
Some of these problems can be mitigated through meta-analyses, where results from multiple studies are combined. In 2022, such a meta-analysis was published on the effects of intermittent energy restriction on body weight. It included 16 studies, with between 8 and 68 participants in each, and fasting periods lasting between 2 weeks and 6 months. All studies included a control group with a regular diet. Weight loss from intermittent energy restriction ranged from 0.5 kg to 13.9 kg, while the control group lost between 1.9 kg and 11.8 kg. Statistically, there was no significant difference in weight loss between intermittent energy restriction and regular diets, nor between the different types of fasting (1:1 fasting, 5:2 fasting, or time-restricted eating). Additionally, participants found it harder to stick with intermittent energy restriction over time, just as they do with regular diets.
What does Neatic recommend concerning intermittent energy restriction?
Many claims about the positive health effects of intermittent energy restriction are exaggerated and not backed by scientific evidence. In particular, there is no convincing proof that it leads to lasting weight loss or works better than regular diets.
However, if you are interested in trying intermittent energy restriction, you can certainly combine it with Neatic.
Bibliography
Elortegui Pascual, Paloma; Rolands, Maryann R.; Eldridge, Alison L. et al. (2023): A meta-analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time-restricted eating for weight loss. In: Obesity (Silver Spring, Md.) 31 Suppl 1 (Suppl 1), pp. 9-21. DOI: 10.1002/oby.23568.