Intermittent fasting is a process that enables you to lose weight by mixing a low-calorie diet with unrestricted eating throughout the week. The issue is that many individuals tend to disobey this diet without even wanting it.
Intermittent fasting is a way of losing weight that favours flexibility over calorie counting. It restricts the time you are allowed to eat, which reduces calorie intake by limiting opportunities to eat.

Intermittent fasting

While intermittent fasting has as main purpose to make the large calorie deficit remain unchanged after a period of fasting or low-calorie dieting, studies have shown that actually a combination of eating just a bit more and doing less physical activity can help recover half of this calorie deficit.

Recovering calorie deficit

When deciding on the best way to lose weight, intermittent fasting might be just the proper way for you. Due to its flexibility, this type of diet enables you to lose weight while still enjoying good meals. 
However, it is entirely up to you to decide on the outcome of the diet, whatever this is.

Intermittent fasting and its flexibility

<figure><img src="https://images.theconversation.com/files/331792/original/file-20200430-42935-vqb4mb.jpg?ixlib=rb-1.1.0&amp;rect=0%2C82%2C6902%2C4352&amp;q=45&amp;auto=format&amp;w=496&amp;fit=clip" width="496" height="313"><figcaption dir="ltr">
 
 <a class="source" href="https://www.shutterstock.com/image-photo/204-fasting-diet-concept-one-third-1594385533" dir="ltr">Marcin Malicki/Shutterstock</a>
 </figcaption></figure>Intermittent fasting is a way of losing weight that favours flexibility over calorie counting. It restricts the time you are allowed to eat, which reduces calorie intake by limiting opportunities to eat. That’s the theory, at least.A popular version of intermittent fasting is <a href="https://www.bbcgoodfood.com/howto/guide/what-52-diet" dir="ltr">the 5:2 diet</a>, which involves eating a very low-calorie diet (about a quarter of usual calorie intake) for two days each week and unrestricted eating on the other five days. This approach has worked well for some people, but not everyone. In our <a href="https://www.sciencedirect.com/science/article/pii/S0195666319315636?dgcid=author" dir="ltr">latest study</a>, we found that people cheat on their intermittent fasting diet, without realising it.Conducted over three days, the study aimed to find out how eating and physical activity changed around a period of calorie restriction. A group of male participants completed two trials. On the first trial day, they were told they would have a very low-calorie diet (about 700 calories) the following day. Throughout the rest of the day, we tracked how much the participants ate and we assessed their hunger before and after each meal. Their physical activity was also monitored throughout the day. The next day, participants ate the very low-calorie diet, and we monitored their physical activity. The morning after completing the low-calorie diet day, we measured their food intake at an unrestricted breakfast and assessed their hunger before and after the meal. <figure><img alt="" src="https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=400&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/332307/original/file-20200504-83751-14hk5yd.jpg?ixlib=rb-1.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=503&amp;fit=crop&amp;dpr=3 2262w" width="600" height="400"><figcaption dir="ltr">
 Food intake was measured at an unrestricted breakfast.
 <a class="source" href="https://www.shutterstock.com/image-photo/closeup-on-young-womans-hands-she-188434373" dir="ltr">Lolostock/Shutterstock</a>
 </figcaption></figure>Each participant also completed a control trial that followed the same method. During the control trial, participants ate a typical diet (about 2,800 calories) instead of a very low-calorie diet. We found that participants ate 6% more on the first day of the study and 14% more at the unrestricted breakfast on the low-calorie diet trial. This was despite hunger levels before and after each meal being similar to the control trial. This suggests participants ate more because they knew food intake would be restricted the following day, rather than because they felt hungrier. Physical activity was also 11% lower the day before eating the low-calorie diet, and 18% lower while eating the low-calorie diet. Interestingly, low-intensity physical activity, such as washing the dishes, which tends to be spontaneous behaviour rather than consciously planned activities, was the most affected component of physical activity. We found changes in eating and physical activity behaviour occur before, during and after a day of low-calorie dieting. These behavioural changes reduce the likelihood of intermittent fasting leading to weight loss. For a diet to lead to weight loss, calories burned must exceed calories consumed to produce a calorie deficit. Intermittent fasting diets assume that the large calorie deficit produced by fasting or very low-calorie dieting is not recovered during the unrestricted period, so the calorie deficit is preserved. But our study shows that eating a little more and reducing spontaneous physical activity may be enough to recover almost half of this calorie deficit. The calorie deficit may also be reduced further <a href="https://academic.oup.com/ajcn/article/104/6/1545/4564664" dir="ltr">at subsequent meals after a very low-calorie diet day</a>.<h2>Worth the sacrifice?</h2>Earlier studies support our findings. <a href="https://academic.oup.com/ajcn/article/100/2/539/4576482" dir="ltr">Skipping breakfast for six</a> weeks was shown to reduce physical activity and increase calorie intake at later meals. This was enough to fully compensate for calories skipped at breakfast. This raises the question: is fasting or severe calorie restriction worth the sacrifice?Weight loss from any diet is always likely to be lower than expected. Compensatory mechanisms defend against a calorie deficit far <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/oby.21653" dir="ltr">more strongly than a calorie surplus</a>. In scientific studies of intermittent fasting, participants are often guided by a dietitian on how many calories they should eat on the unrestricted days. Even with this support, participants in these studies <a href="https://www.mdpi.com/2072-6643/11/10/2442/htm" dir="ltr">still lose less weight than would be expected</a> if the calorie deficit had been fully preserved. Our study highlights what and when compensatory behaviours occur. This information can be used to improve the effectiveness of intermittent fasting diets. Being more mindful when eating before and after a period of calorie restriction and incorporating exercise into diet plans, could help increase the likelihood of intermittent fasting leading to weight loss. Intermittent fasting is not a miracle diet, but some people may benefit from its flexibility, and with a few minor adjustments, it could be even more effective. If you’d like to take part in our next study, exploring pre-lockdown and during-lockdown exercise and nutrition habits, <a href="https://ntusurvey.onlinesurveys.ac.uk/exercise-nutrition-behaviours-ntu" dir="ltr">please click on this link</a>. You must be 18 years or older and have taken part in regular physical activity before the lockdown.

Intermittent fasting: if you're struggling to lose weight, this might be why