How can we use the simple and easy fasting weight loss method that allows us to eat and drink as much as we want without harming our health?

Author: Wu Jia (registered dietitian), Fan Zhihong

Braised spareribs, cheesecake, spicy hot pot, skewers, ice cream... When it comes to foods that you can't eat when losing weight, everyone can list a bunch of them. It is these many "can't eats" that make losing weight a test of people's willpower.

In recent years, a weight loss method that claims to not require any dietary restrictions has become very popular, attracting many celebrities.

This is what we are going to talk about today: the "intermittent fasting method for weight loss."

Intermittent fasting is a diet that is designed to reduce weight. It literally means not not eating for many consecutive days, but intermittently or periodically, within a certain period of time, the calorie intake is much lower than the normal daily diet level. Common intermittent fasting methods include alternate-day fasting, 5:2 fasting, and time-restricted feeding.

Hollywood star "Wolverine" Hugh Jackman played Wolverine for 17 years. For this role, Hugh Jackman needed to undergo long-term high-intensity training, control his diet and maintain his figure. The intermittent fasting weight loss method is one of his "secrets" to maintain his figure.

The reason why these celebrities have a special liking for this method is mainly because of its convenience.

Due to work reasons, many people find it difficult to cook according to a nutritional recipe every day. Except for breakfast, lunch and dinner are often boxed meals or fast food, and they cannot control the content and calorie value of the food.

In comparison, intermittent fasting is relatively simple.

For example, alternate-day fasting means you can eat whatever you want one day, and fast the next day, eating only 1/4 to half of your normal amount. Eat more one day, eat less the next, and so on.

For example, the 5:2 intermittent fasting method means eating whatever you want to satisfy your hunger on 5 days of the week, regardless of calories, and eating any meat you want, and eating very little food on the other two days (these two days cannot be consecutive), with calories roughly equivalent to about a quarter of a normal diet. Most people feel that this method is feasible. Therefore, it is the most accepted intermittent fasting method.

For example, the 8-hour daily fasting method restricts the eating time period. You can eat whatever you want during the 8 hours of the day, and you cannot eat anything for the next 16 hours.

However, what are the health effects of intermittent fasting? Is it as magical as the legend says? This requires experimental data to speak.

After checking the literature, I found that there have been many studies on intermittent fasting in recent years, but most of the experimental designs are not rigorous enough. Here I will only show you the research conclusions of several systematic reviews and summary analyses in the past two years.

Let’s first talk about the impact of intermittent fasting on weight.

In 2018, an article in the "JBI Database of Systematic Reviews and Implementation" conducted a meta-analysis of studies on intermittent fasting [1]. The article searched for relevant studies starting in November 2015, and 6 studies met the criteria. The specific methods of intermittent fasting vary, some are fasting every other day, some are fasting two days a week, and some are fasting 3-4 days a week; the duration of the study ranges from 3 months to one year. Four of the studies compared intermittent fasting with the traditional weight loss method of reducing calories every day, and two studies compared intermittent fasting with no weight loss measures.

The result is: there is a significant difference in the weight of the subjects using the intermittent fasting method compared to no weight loss measures at all. The average weight loss is 4kg. However, there is no significant difference in the effect compared to the traditional calorie reduction method. The researchers believe that the intermittent fasting method and the traditional energy control method are similar in terms of reducing weight, waist circumference and body fat.

Let’s talk about the impact of intermittent fasting on blood lipids.

In September 2020, a report in Nutrition magazine reviewed the relevant research on intermittent fasting and blood lipids [2]. The researchers found that 34, 33, 35, and 33 intermittent fasting studies that met the quality standards measured changes in low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), and triglycerides (TG). The duration of these studies ranged from 4 weeks to 12 months.

Studies have confirmed that both intermittent fasting and traditional calorie reduction methods can help improve blood lipid levels.

——For lowering total cholesterol, both traditional calorie reduction and intermittent fasting methods have significant effects, but the former is more effective;

——Traditional calorie reduction and weight loss methods have significant effects on lowering triglycerides, while intermittent fasting methods have no significant effect;

- Both methods are effective in lowering LDL cholesterol, and the difference in effectiveness is not significant;

——Neither method is effective in increasing high-density lipoprotein cholesterol.

Of course, the specific effects vary depending on factors such as the subject's health status, initial blood lipid levels, dietary calories, etc.

Then look at the impact of intermittent fasting on physical strength.

"Man is iron and rice is steel. If you don't eat for a meal, you will be hungry." Will this alternating eating and drinking affect people's muscle level and athletic ability?

In May 2020, an article published in the journal Nutrients summarized and analyzed the research on intermittent fasting. The article retrieved relevant studies between 1980 and 2019, and analyzed 28 studies that met the criteria among the 7,789 published studies retrieved. The article found that intermittent fasting does not affect muscle strength and anaerobic capacity, but may also improve aerobic exercise capacity [3].

In 2019, the New England Journal of Medicine published a review discussing the health effects of intermittent fasting. After reviewing relevant studies, the article concluded that intermittent fasting has been shown to improve obesity, diabetes, cardiovascular disease, cancer, and neurological diseases, including blood pressure, resting heart rate, high-density and low-density lipoprotein cholesterol, triglycerides, diabetes, insulin levels, and insulin resistance [4].

However, the research results on the effect of intermittent fasting on blood sugar control are inconsistent. Some believe that it is beneficial, while others believe that it has no beneficial effect. The beneficial effect comes from the fat loss brought about by intermittent fasting, but if muscle loss occurs at the same time, it may offset the good effect of fat loss. Therefore, the effect may be related to the nutritional intake during intermittent fasting, but there are currently no in-depth research reports on this aspect.

I have to remind you here: although this method has the support of a large number of experts and has research data for up to one year, after all, they are experiments under the guidance of experts, and are still different from ordinary people's random intermittent fasting.

This is because the body needs more than 40 nutrients and multiple health factors every day. It is far from enough to just consider the amount of calories. During the intermittent fasting period, what specific food you eat on a daily basis is also very important. If you do it well, it may help you lose weight, but if you do it poorly, you may suffer from malnutrition.

So, what should we do to get the health benefits of intermittent fasting?

As mentioned before, intermittent fasting is intermittent fasting. Common methods include alternate-day fasting, 5:2 fasting, intra-day fasting, etc. Among them, alternate-day fasting is less used because half of the days will be affected, and better gastrointestinal function is required to adapt to this diet with a large change in food intake.

Key points for using the 5:2 intermittent fasting method:

This method is more convenient, with normal eating for 5 days and light fasting for 2 days in a week, so there are many users. However, if you want to achieve a healthy effect, it is recommended to do the following:

Key point 1: You must eat enough nutrition to be fully satisfied during the other 5 days. You must not be hungry or just full during the five days and then fast for two days. If you eat less or are already malnourished, fasting days will be particularly painful; if you eat enough nutrition and your body has reserves, fasting days will be easy to tolerate.

Point 2: The protein supply on non-fasting days must be sufficient, and fat does not need to be restricted, but it is still not recommended to eat foods with low nutritional value, fried foods, sweet drinks, etc. In other words, calories do not need to be controlled, but things with no nutrition but only calories should not be eaten casually. Because intermittent fasting can only make up for the problem of excessive calories and adjust metabolism to a certain extent, but it cannot increase nutrition.

Point 3: Eat less on fasting days. On the day of light fasting, only consume about 1/4 of the normal amount of calories, that is, 500 kcal for girls and 600 kcal for boys. Studies have shown that the number of fasting days is not the most important, but eating less on fasting days is important.

Point 4: Fasting days must be non-consecutive, that is, you cannot fast on the first day and then fast again on the second day. If you eat too much on a certain day, especially if it is greasy, you should fast on the second day. This will not be too painful and will help eliminate the adverse effects of overeating.

Point 5: If you don’t eat much fruit and vegetables on weekdays, you can focus on eating more fruit and vegetables on fasting days. If you rarely eat whole grains on a daily basis, you can cook some porridge with whole grains on fasting days.

Here is a sample high-satiety recipe for a fasting day, suitable for those who feel uncomfortable eating only raw and cold food and are sensitive to hunger.

Spinach and egg soup for breakfast (1 egg 60g, spinach 100g, sesame oil 1g)
1 small bowl of thinner red bean porridge (10 grams of red beans, 10 grams of glutinous rice)

Lunch: 1 small bowl of thin red bean porridge (10 grams of red beans, 10 grams of glutinous rice)
Chicken, tomato and cauliflower (cook 50g chicken breast first, add 100g cauliflower, 2g oil and 100g tomato at the end after the chicken is cooked)

Dinner: Shrimp, rapeseed, mushroom and tofu soup (50g southern tofu, 200g rapeseed, 2g dried shrimp, 50g mushroom, 2g oil)
1 small apple 150g

Total calories for the day: about 500 kcal. Please note that you should reduce the amount of salt when cooking soup, just enough to taste a little salty.

Key points for using the intraday fasting method:

Many people use this method. The most commonly used one is the 8:16 time-restricted eating method, which involves eating whatever you want within 8 hours and not eating for the remaining 16 hours.

Point 1: This method must ensure that all nutrients are consumed within 8 hours, and the supply of protein, vitamins and minerals cannot be reduced.

Key point 2: You can eat two or three meals within 8 hours. Try to eat enough food for the main meal.

Point 3: Reduce the intake of low-nutrition foods and increase the nutrient density of foods. Don’t just eat cookies, snacks, potato chips, fried foods, etc. during the 8 hours of intermittent fasting.

Point 4: Try to fast at night. Studies have shown that eating more in the morning and at noon is less likely to make you fat and better control your blood sugar. So it is better to skip dinner than breakfast. Try to eat high-calorie foods at breakfast and lunch.

Point 5: During the ten hours of fasting, you can only drink water, not energy drinks, such as coffee with sugar and milk, or black tea with creamer. It is not recommended to drink black coffee and strong tea, because they will cause hunger on an empty stomach. It is also not recommended to drink drinks with sweeteners, because they cannot provide energy, but may increase appetite.

If you occasionally cannot eat within 8 hours, try to eat within 10 hours and do not eat snacks between meals.

Many people can still do this eating habit if they go to bed early and get up early, eat enough food within 8 hours, and have a good nutritional balance.

An important conclusion must be emphasized: According to current research results, the overall health effect of intermittent fasting is not better than a nutritionally balanced energy-reducing diet. It is only popular because it is relatively easy to operate and does not require too many changes to daily dietary habits and work arrangements.

Interestingly, a study found that compared with the seemingly easy intermittent fasting weight loss method, people who adopted the traditional weight loss method, that is, continuous energy-reduced nutritious meals, had significantly higher mental health scores. This suggests that although continuous weight loss methods may be a little troublesome, after sticking to them, good eating habits can be formed, which will lead to improved nutrition and overall quality of life.

Finally, I would like to emphasize one more thing: the current research on intermittent fasting weight loss methods is conducted on adults who are overweight, obese, or close to the upper limit of BMI and who eat too much on a daily basis. It is not suitable for promotion to all people.

It is not suitable for people with normal weight or even thin body. It is not suitable for people with insufficient muscle mass. It is not suitable for people with malnutrition.

In addition, minors, pregnant women, nursing mothers, patients with depression, gastrointestinal diseases, gallbladder diseases, liver and kidney diseases, and people with poor blood sugar control should use it with caution. People with high blood pressure, heart disease and other problems should also do relevant safety assessments in advance and follow the doctor's advice.

References:

1 Leanne Harris, Sharon Hamilton, Liane B. Azevedo, et al. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis, JBI Database of Systematic Reviews and Implementation Reports. 2018, 16(2): 507-547

2 Haiyan Meng, Lei Zhu, Hamed Kord-Varkaneh, et al. Effects of intermittent fasting and energy-restricted diets on lipid profile: A systematic review and meta-analysis. Nutrition, 2020, 77(9): 110801

3 Joana M, Effects of Intermittent Fasting on Specific Exercise Performance Outcomes: a Systematic Review Including Meta-Analysis. Nutrients, 2020, 12(5): 1390

4 Rafael de Cabo, Effects of Intermittent Fasting on Health, Aging, and Disease. The New England Journal of Medicine, 2019, 381:2541-2451.

Reprint/ Cooperation please contact

[email protected]