You Are When You Eat? How Intermittent Fasting Affects Weight Loss

"You are what you eat," is an old adage that gets hammered into our heads at a young age — and for good reason, according to pretty much every health expert on the planet.

近年来，虽然，信条，已经开始转向了一下：当然，质量和数量显然非常重要的膳食因素。但许多健康专家开始认为时机可能也同样至关重要。“我们一直专注于whatwe eat, but almost never onwhen我们吃的，”迈克尔Crupain，MD，MPH，职工的医疗单位在长The Dr. Oz Showand author of什么Eat When，tells LIVESTRONG.com.

There are a number of reasons why this thinking is changing, Dr. Crupain explains, including new scientific findings and the rising popularity of the ketogenic or"keto" diet其争议的组件之一：间歇性禁食。

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禁食是什么新东西 - 其实，这个概念可以追溯到远古时代。但间歇性禁食方式的结构方法（IF），在其中限制食用到一个特定的时间内（一天或一周中的几天的某些时段），已与酮饮食的兴起得到了普及最近。这个想法是从食物中弃权更长的时间比正常时间有助于把你的身体成state of ketosis，促使它燃烧脂肪供能，而不是碳水化合物。

But not everyone who practices IF follows theketo diet。Other purported benefits of IF on its own include weight loss, lower blood pressure, improved mental state, reduced inflammation and improved cellular repair, according to a December 2019 review published in新英格兰医学杂志。

The review notes that human studies on IF are limited, and much more research needs to be done, but the evidence so far shows that the protocol may also improve insulin sensitivity (which might help reduce the risk of2型糖尿病) and reduce belly fat.

Crupain博士属性的IF运动到不断发展的科学supporting the idea that our bodies' circadian rhythm — aka our internal clock — influences our health.

“我们的昼夜节律不仅仅是睡眠，这实际上改变了我们的新陈代谢全天，使whenwe eat can make a big difference," he explains. "By eating in line with when our body is best primed to use food, we basically hack our metabolism and optimize health. By contrast, eating out of sync with our circadian rhythm can lead to weight gain and other health issues."

越来越多的研究与weig链接如果ht loss, although most studies so far have been limited to a small number of participants and short time frame.

In one study, published December 2019 inCell Metabolism，researchers had 19 people with metabolic syndrome fast for 10 hours each day for 12 weeks. They found that this amount of fasting promoted weight loss and also reduced waist circumference, body fat percentage andbelly fat。(Beyond weight-loss benefits, the participants also reduced theirblood pressureand total cholesterol levels, got better sleep and saw improved blood sugar and insulin levels.)

Dr. Crupain points to a larger study published October 2013 in theInternational Journal of Obesity，which monitored the eating habits of 420 individuals over a 20-week weight-loss program. Participants consumed the same food but were grouped into two categories: early-eaters, who consumed their lunch before 3:00 p.m., and late-eaters, who dined after that time. Researchers found that those who ate earlier lost significantly more weight — 25 percent more to be exact — than those who ate later in the day.

“也许不是刚性‘无下午4:00后食用’规则，古老的格言“像国王，午餐像商人，晚餐像乞丐早餐”将是某种在你自己的生活方式去尝试。”

和12的2019年10月的荟萃分析研究IF刊登在Journal of Clinical Medicine，发现，相比控制饮食，禁食间歇帮助显著下降捕鱼欢乐季 and fat mass, although the review was limited to people without diabetes.

Some studies have suggested that IF's weight-loss benefits are due to increased calorie burn. But others, including a small July 2019 paper published in肥胖，contend that, somewhat counter-intuitively, going longer without eating actually降低appetite.

In the report, researchers found that after restricting eating to between 8 a.m. and 2 p.m., people had lower levels of the hunger-linked hormone ghrelin in the morning and higher levels of a satiety hormone at night compared to when they ate within a 12-hour window instead. However, because only 11 people were included in the study, more research is needed to determine whether or not IF truly tamps down appetite.

In addition to keto and intermittent fasting, there are a few other diets that put a serious emphasis on meal timing and fasting.

1. Crupain博士什么Eat When

The concept of "fasting" can be a little daunting to some people, but it shouldn't be, according to Dr. Crupain, whose book outlines his method of food timing and offers readers a few simple principles of how to eat in alignment with this clock.

首先，在白天消耗你的膳食。“夕阳西下我们的昼夜节律，我们的身体被灌注到吃饭的时候，太阳出来，快当它是黑暗的，”他解释说。

其次，他强调吃在当天早些时候多，少后来的重要性。早餐和午餐应该是你最大的一天的饭菜，和晚餐最小。“理想情况下，你应该吃你的传统晚餐食品 - 蛋白质，蔬菜等-earlier在白天和避免简单碳水化合物如糖和饱和脂肪，”他说。

Following these two principles, Dr. Crupain points out that you should get a window of at least 12 hours or more of fasting each day.

2. Alternate-Day Fasting

This eating method has been popular for a few decades, and involvesalternating days of fasting（在这里你只消耗无热量饮料，如咖啡和水）通常吃的日子。

然而，尽管其受欢迎程度，很少有科学证据支持声称，它可以与减肥或保持体重的帮助，或提高heart health。

3. The 5:2 Diet (aka The Fast Diet)

In the bookThe Fast Diet，by writer Mimi Spencer and Michael Mosley, MD, the duo explain that fasting two days each week induces your body to burn fat and promotes weight loss.

On this diet, you will eat normally five days a week and then consume just 500 to 600 calories on the other two days. Those calories can be consumed during one sitting or spread out over the day. You can also choose when to do the fast days, staggering them throughout the week or doing them consecutively.

In one study of 150 people, published November 2018 in美国临床营养学杂志研究人员发现，这种类型的禁食只是作为一种低热量饮食减肥和预防代谢性疾病有效。

4. The ProLon Diet (aka the Fasting Mimicking Diet)

Created by Valter Longo, PhD, an Italian biologist and researcher, theFasting Mimicking Diet据报道，给人的身体禁食，同时还为它提供营养的所有健康的好处 - 低碳水化合物和全富含蛋白质和植物性食物为主。

膳食包括螺母条，汤，羽衣甘蓝饼干和橄榄。隆戈甚至卖他的网站上五天，预包装餐包，为了使饮食容易。声称的好处包括增强的性能，减肥，增强细胞再生，改善代谢健康。

“当你吃不要紧，或当你不吃饭，所有的事情就是你吃多少，”名人训练师吉利安迈克尔斯在最近的一次采访中声明Well + Good。虽然迈克尔不相信间歇禁食会有助于减肥，她也尽量给她的食物摄入量保持在期间早8点和晚8点之间为了牟取了“抗衰老”的好处。

Monica Auslander Moreno, RD, LDN，dietitian and founder of Essence Nutrition, agrees that if you are trying to lose weight, you should focus more on the quality and quantity of the food you are eating than when you are consuming it. "Even the 'best' studies on fasting find weight loss results of just a couple pounds," she tells LIVESTRONG.com.

Morena mentions, though, that restricting your meals to earlier in the day might help you feel more comfortable digestion-wise and improve your sleep. "Perhaps rather than a rigid 'no food after 4:00 p.m.' rule, the old adage 'breakfast like a king, lunch like a merchant and supper like a pauper' would be something to try in your own lifestyle," she suggests.

When it comes to your diet, you should always take a variety of factors into consideration, with timing being just one of them. While science has yet to definitively conclude whether fasting diets are beneficial,most experts will agreethat consuming food during daylight hours is a better option than at night.

If you decide you want to tap into fasting, though, be sure to speak with your health practitioner or a medical expert first, especially if you have any preexisting health conditions.