生酮饮食101：酮的完整科学指南| Everyday Health

One enduring buzzword to hit the diet world seems to be “keto” — referring to the high-fat, low-carb ketogenic diet. With claims that you can eat all the fat you want, never feel hungry again, and even boost your athletic performance, thediet为每个人承诺一些东西。

But what exactly is the ketogenic diet, and is the weight loss program right for you? Let’s take a closer look before you attempt to make over your eating habits and lifestyle.

What Is the Ketogenic Diet?

生酮饮食基于这样的原理：通过耗尽其主要能源来源的碳水化合物的身体，您可以迫使人体燃烧脂肪以燃料，从而最大程度地减轻体重。当您食用含有碳水化合物的食物时，人体会将这些碳水化合物转化为葡萄糖或血糖，然后将其用于能量。

Because glucose is the simplest form of energy for the body to use, it’s always used for energy before your body turns to stored fat for fuel.

On a ketogenic diet, the goal is to restrictcarbohydrateintake so that the body must break down fat for energy. When this occurs, fat is broken down in the liver, producing酮, which are by-products of your metabolism. These酮are then used to fuel the body in the absence of glucose.

How to Follow the Ketogenic Diet

有几个types of keto，但从本质上讲，要实现ketosis，您必须严重减少所吃的碳水化合物量。（您可以使用生酮计算器to create a custom food plan.) Data suggest the average American man age 20 or older consumes 46.4 percent of his daily calories from carbs, and the average American woman older than 20 consumes 48.2 percent of her daily calories from carbs.

But in the classic ketogenic diet, which was originally used to manage seizure disorders, 80 to 90 percent of calories come from fat, 5 to 15 percent come from protein, and 5 to 10 percent come from carbohydrates.

A modified version of the ketogenic diet, which allows you to eat protein more liberally — at 20 to 30 percent of your total calories — with the samecarbohydrate限制,更普遍的使用d version of the diet today. Some of the aims of the latest version of the ketogenic diet are weight loss, weight management, and improved athletic performance.

什么是酮症？

The ketogenic diet forweight lossis based on the idea that driving the body intoketosiswill maximize fat loss. Ketosis is a normal metabolic process that occurs when the body does not have enoughglucosestores for energy. When these stores are depleted, the body resorts to burning stored fat for energy instead of carbs. This process produces acids called ketones, which build up in the body and can be used for energy.

如何You Know if You’re in Ketosis?

弄清楚你的酮症, check your urine for ketones. You can purchase ketone strips online or from a retail pharmacy. A strip that tests positive for ketones will indicate you have reached a state of ketosis.

Many people associate elevated ketones with a糖尿病medical emergency known as ketoacidosis, but nutritional ketosis associated with a ketogenic diet and糖尿病ketoacidosisare very different conditions.

Ketosis vs. Diabetic Ketoacidosis (DKA)

对于患有糖尿病的人，迅速上升的酮水平会表明需要立即医疗护理的健康危机。当缺乏或不足的激素胰岛素（或人体过于抗性无法胰岛素以使其允许其将葡萄糖驱动到细胞中以获取能量）时，人体不能将葡萄糖用于燃料。胰岛素有助于将葡萄糖运送到我们的细胞和肌肉中，以获得能量。取而代之的是，在这种情况下，人体通过酮症的过程来燃烧储存的脂肪，以获得能量，从而导致体内大量酮。

随着酮积累在糖尿病患者的血液中，它们会导致血液变得更加酸性，这可能导致称为酮症酸中毒的疾病。这种情况可能是致命的，应立即处理，如2021年5月发表的文章Endotext指出。

Learn More About Ketosis and How the Keto Diet Works

Potential Health Benefits and Risks of the Keto Diet

If you search online for the term “keto diet,” you'll find a lot of health claims associated with the ketogenic diet. But before you give this approach a try, it’s important to know what the science suggests about how it may affect your health. Namely, you'll want to know about potential keto diet dangers.

Risk: You May Suffer Fatigue and Other Symptoms as a Result of the Keto Flu

开始生酮饮食的最常见副作用之一是“keto flu。” This term describes the often unpleasant, fatigue-inducing symptoms that occur as the body adjusts from a high-carbohydrate to alow-carbohydrate diet。Duringketo flu，人体储存的葡萄糖开始耗尽，身体开始适应产生和利用酮作为能量的能量。

Symptoms of the keto flu include headache, fatigue, dizziness, sleep problems, heart palpitations, cramps, and diarrhea. These side effects usually diminish and resolve in about two weeks.

但是，为了减轻任何不适的影响，只需考虑慢慢过渡到生酮饮食，而不是急于改变饮食习惯。通过逐渐降低碳水化合物的摄入量并逐渐增加饮食脂肪的摄入量，您可以在负面影响下过渡，并可能完全防止酮流感。

Risk: You May Experience Constipation if You Don’t Eat Enough Fruits and Veggies

The removal of many grains and fruits with such a large emphasis on fats can bring about its own set of胃肠道副作用。Keto constipation and diarrheaaren't uncommon. “If not done properly — with most of your carbohydrates coming from fiber-rich vegetables — you may not be getting enough fiber, which can lead toconstipation,” saysChris Mohr, RD, PhD是位于肯塔基州路易斯维尔的体育营养师和Mohrresults.com的共同所有人。

Risk: You Could Develop Dangerous Nutrient Deficiencies

Eliminating food groups can be problematic. “Ketogenic diets are often low in calcium,vitamin D, magnesium, and叶酸, which over time can lead to nutrient缺陷if the diet is not planned carefully,” addsMarie Spano, RD, a sports performance nutritionist in Atlanta.

风险：您可能会通过饮食对动物脂肪和蛋白质的重视伤害您的心脏

Reliance on a diet rich in animal fats and proteins may also have a negative impact on heart health, research shows.

“This diet is not for anyone who is at risk of developing cardiovascular disease or who has already been diagnosed with it,” Spano cautions.

This means that if you have risk factors for heart disease — such as elevated胆固醇,high blood pressure (hypertension), or a strong family history of the disease — you should use caution when following this diet. The diet's heavy reliance on fat, especiallysaturated fat, can raise胆固醇levels, further increasing your chances of developing heart disease in the future.

A 2019 position statement from the National Lipid Association Nutrition and Lifestyle Task Force noted that research has found low-carb and very low carb plans (which keto fits into) have mixed effects on blood cholesterol levels, with some studies finding that these diets raise cholesterol.

RELATED:古饮食对心脏健康有益吗？

Risk: You May Experience Dangerous Low Blood Sugar if You Have Diabetes

对于任何患有糖尿病的人，讨论饮食变化，尤其是那些像生酮饮食所需的那样戏剧性的变化 - 与您的医疗保健团队至关重要。由于碳水化合物被分解为血液中的葡萄糖，因此从饮食中切割碳水化合物可能会导致水平迅速崩溃，具体取决于您当前的药物治疗方案。这样的改变可能需要对药物和胰岛素进行大量调整，以防止危险的副作用，例如低血糖，称为hypoglycemia。

Risk: You May Experience Weight Cycling and Negative Effects on Your Metabolism

除了身体健康的变化之外，生酮饮食的最大关注点之一可能是长期依从性。“这是一种非常困难的饮食，坚持和维持。合规性是一个挑战，因为它是如此限制。” Mohr博士解释说。

Following a strict减肥然后，当饮食变化过于限制时，迅速恢复到旧习惯，可能会导致所谓的体重循环或溜溜球节食。根据一项研究Preventive Medicine Reportspublished in December 2019.

Benefit: You May See Improvements in Your Athletic Performance

For athletes, research on the keto diet highlights potential improvements in athletic performance, especially when it comes to endurance activities. An article in theBritish Journal of Sports Medicine发现生酮型饮食使耐力运动员主要依靠储存的脂肪来获得能量，而不必加油simple carbohydratesduring endurance training and competition, and saw improved recovery times.

That said, a review published in October 2020 inSports结论是，尽管酮饮食可以帮助运动员减轻体重和体内脂肪，但没有结论性的证据表明饮食方法可以改善或损害健康和表现。

好处：您可能会快速减肥 - 但不一定比其他饮食量还要多

If you’re looking to lose weight, one benefit the ketogenic diet may offer is appetite suppression. A review of this form of eating suggests it may help decrease appetite, but how this actually happens needs to be studied further.

Very low calorie ketogenic diets may help people who are overweight or have obesity reduce theirBMI, decrease the circumference of their waist, and lower levels ofA1C, total cholesterol,triglycerides, and blood pressure, notes a review and meta-analysis published in March 2020 in内分泌和代谢性疾病的评论。

但是，当涉及体重减轻（许多人的最大酮卖点之一）时，生酮饮食的好处可能与任何其他饮食计划都没有太大不同。Spano说：“从这种饮食中，无法从中获得神奇的减肥益处。”“生酮饮食可以通过限制食物选择来帮助减肥，从而有助于减肥，从而减少卡路里。”

Mohr agrees. “Cutting so many carbohydrates is a big reduction in calories,” he says, adding that this effect will lead to a loss ofwater weight在前面，“这就是为什么人们喜欢这种饮食产生的体重减轻的立即反应的原因。”也就是说，减少卡路里并不总是如此，因为如果您吃更多卡路里密集的食物（即脂肪），总体上消耗更多的卡路里很容易。一项于2021年2月发表的一项小型研究Nature Medicinefound that people ate almost 700 fewer calories per day on a plant-based low-fat diet compared with a low-carb one consisting of mostly animal fats.

Benefit: You May See Better Blood Glucose Control if You Have Type 2 Diabetes

For individuals with diabetes, adapting a very low carbohydrate diet, such as the ketogenic diet, may offer some benefits when it comes to glucose management. For instance, a previous review found that dietary restriction of carbohydrates may reduce or eliminate the need for medication in individuals with type 2 diabetes.

了解有关酮饮食可能的利益和风险的更多信息

常见问题和答案

What can I eat on keto?

In short, a whole lot of fat, a moderate amount of protein, and very few carbs. Some of the best foods to eat on keto include avocado, olive oil, eggs, asparagus, green peppers, and cauliflower. On the flip side, you should avoid foods high in carbs — such as bread, pasta, many fruits, chips, crackers, candy, and cake.

酮饮食安全吗？

For certain people, keto can pose health risks, so talk to your healthcare team first. Some groups that may want to avoid keto are: anyone with an underlying health condition like diabetes, pregnant or breastfeeding women, those who don't have a gallbladder, anyone with a history of an eating disorder, and anyone taking prescription medication.

为什么酮症不好？

It's not bad exactly — unless you have kidney disease, as this metabolic state can strain the organs. But ketosis is essentially a natural metabolic state in which your body, in the absence of sufficient carbs, begins relying on fat for energy. It's different from diabetic ketoacidosis, which is a health emergency.

我如何开始酮？

Your best chance for success on such a restrictive diet as keto is to find a registered dietitian familiar with the eating style. He or she will help you gradually change your diet so you're eating fewer carbs and more fat, staying hydrated, managing any keto side effects that come up, and meeting all your nutritional needs.

What are the side effects of a ketogenic diet?

酮饮食的臭名昭著的是酮流感。当您的身体适应酮症时，您会收集症状（想想便秘，头痛，恶心）。放心，您的症状将在几周内通过，但是注册的营养师可以帮助您最大程度地减少它们。

Is the Keto Diet Right for People With Diabetes?

因为酮饮食的主要宗旨是计数和切割碳水化合物（一种控制血糖的一种常用方式），这种饮食方法已经越来越受欢迎lower their A1C, which is the two- to three-month average measurement of blood sugar levels. Indeed, research suggests this diet may lead to fast weight loss and potentially lower blood sugar for people with the disease.

But dietitians warn the keto diet also comes with risks that are specific to people managing diabetes, including possible drug interactions and potentially dangerous low blood sugar if you're on medication, as well as kidney damage in people whose kidneys are dysfunctional because of elevated ketones in the blood.

另外，由于尚未长期研究酮，研究人员不知道饮食是否会导致营养缺陷for those with or without diabetes.

If you're considering trying the keto diet and you have diabetes, it's crucial to consult your diabetes-care team before doing so to make sure it's a safe and effective eating approach for you.

了解有关酮饮食如何使2型糖尿病患者受益的更多信息

如何开始生酮饮食

Here are some other things to know before you try this restrictive eating plan.

您可以坚持碳水化合物的限制吗？

Following a diet that drastically restricts carbohydrates requires carefully monitoring your food choices to ensure you are meeting your nutritional needs. Work with a registered dietitian to make sure you follow this diet in a healthy manner without increasing your risk for complications or negative side effects. You can find a registered dietitian ateatright.org。

It’s important to remember that the goal of any dietary change is to promote a healthy lifestyle, so make sure to select a meal plan you can envision yourself following long term. If you know you will not be able to comply with such stringent carbohydrate restrictions for years to come, the ketogenic diet is most likely not the right choice for you.

What Are the Different Types of Keto Diets?

There are various modifications of the ketogenic diet. The majority of individuals following a ketogenic diet follow the so-called standard ketogenic diet plan, which provides about 10 percent of your total calories from carbohydrates.

Other forms of ketogenic diets include cyclic ketogenic diets, also known as carb cycling, and targeted ketogenic diets, which allow for adjustments to carbohydrate intake around exercise. These modifications are typically implemented by athletes looking to use the ketogenic diet to enhance performance and endurance and not by individuals specifically focused on weight loss.

一般来说，如果您打算遵循生酮饮食，则应目标每天消耗不到碳水化合物的总卡路里的10％。剩余的卡路里应为20％至30％的蛋白质和60％至80％的脂肪。这意味着，如果您每天遵循2,000卡路里的饮食，则不超过200卡路里（或50克）来自碳水化合物，而400至600卡路里应该来自蛋白质，1,200至1,600应该来自脂肪。（有一个原因也称为高脂low-carb diet!)

Is Exercise Involved in the Standard Ketogenic Diet?

Although the ketogenic diet does not explicitly require incorporating fitness into your routine, increasing your physical activity is always important when you want to reduce to or maintain a healthy body weight, according to an article in心血管疾病的进展。

对于耐力运动员来说，向生酮饮食的过渡可能会在训练后削减恢复时间，但是对于休闲运动者来说，向生酮饮食的过渡可能会使您的健身习惯一开始挑战。如果您在开始生酮饮食时感觉到能量水平太多，请减慢碳水化合物的减少，并确保逐渐而不是一次这样做。

您应该期待什么副作用？

To prevent side effects such as the keto flu, begin transitioning your meal plan gradually. Start by understanding how many carbohydrates you consume most days. Then begin slowly reducing your carbohydrate intake over a period of a few weeks while gradually increasing your intake of dietary fat to keep your calories the same. You should also make sure to seek guidance from a professional to make sure this plan works for you and your health goals. “See a dietitian and adapt the diet to fit your long-term needs,” Spano recommends.

在尝试酮饮食之前，请了解有关初学者应该知道的知识的更多信息

What to Eat on the Standard Ketogenic Diet

生酮饮食不是商业进餐计划，因此开始这种饮食没有成本或会员费。但是，根据您目前的饮食习惯，这种饮食方法可能会增加您的食物账单。

Because manyprocessed foodsare not considered ketogenic diet friendly, a switch to buying more whole, unprocessed foods may seem expensive, especially with the emphasis on high-fat and protein-rich foods.

In-season, fresh produce, along with frozen vegetables, which can be just as healthy as their fresh counterparts, will help reduce your costs. Although nuts, seeds, and animal proteins such as beef can drive up the grocery bill, bulk buying can help you save on these items as well.

The ketogenic diet relies heavily on dietary fat. Because high levels of animal fat in the diet have been associated withincreased levels of cholesterol, aiming to include a good variety of plant-based fats can be helpful. Plant-based oils such as olive oil andavocadooil provide healthy fat for cooking anddressings。

Adding fat-rich foods such as avocado, nuts, and seeds can all make for healthful options that will provide you with unsaturated fats along with beneficial fiber. Most fruits are restricted on this plan — there are exceptions, including avocado — but nonstarchy vegetables such as leafy greens should become a staple of your diet.

Lean proteins such as fish, poultry, and grass-fed beef can be included as a source of protein on this diet.

标准生酮饮食的可接受食品清单

Nonstarchy vegetableslike leafy greens, broccoli, cauliflower, cabbage, peppers, mushrooms, onions, and rhubarb
乳制品，includingeggsand cheese
Protein例如牛肉，猪肉，家禽，鱼，贝类和大豆
Nuts and seeds,including walnuts,杏仁，开心果，葵花籽和南瓜种子，椰子（适度）
Fatslike plant-based oils and butter
水果像鳄梨一样berries（适度）和西红柿

您应该避免或限制生酮饮食的食物

加工食品像饼干、炸玉米片和薯片
Sweets,including candy, cookies, brownies, and cake
Grains of all kinds,包括面包，意大利面，大米和藜麦
High-carb fruits像瓜和热带水果
人造甜味剂such as Equal and Splenda

样品三天菜单标准生酮死去t

Day 1

Breakfast: Scrambled eggs with sliced avocado
Snack: Almond butter on celery
Lunch: Spinach salad topped with canned tuna, olive oil, and vinegar
Snack: 1 ounce (oz) string cheese and 1 oz pistachios
Dinner: Sirloin steak paired with sautéed mushrooms, onions, and cauliflower rice

Day 2

Breakfast: Mushroom and cheese omelet with sliced bacon
Snack: ½ avocado
Lunch: Chicken stir-fry with peppers, onions, and peanuts sautéed in peanut oil
零食：1盎司奶酪和1盎司核桃
Dinner: Salmon fillet with oven-roasted Brussels sprouts

Day 3

Breakfast: Keto smoothie made with avocado, full-fat coconut milk,chia seeds, and nut butter
小吃：煮鸡蛋
午餐：芝士汉堡（无面包）在一张生菜床上搭配血豆
小吃：1盎司杏仁
晚餐：鸡胸肉与炒西兰花配对

Learn More About What You Can and Can’t Eat on the Keto Diet

What to Expect if You Try the Keto Diet

While the keto diet can lead to rapid weight loss through ketosis, the plan carries some health risks, including:

营养缺乏
Heart harms
胃肠道issues likeconstipation，和更多。

Because of the health risks involved, experts advise some individuals, such as those with heart disease or individuals who are at a higher risk for it, against trying the keto diet. People with type 2 diabetes should consult their doctor before attempting the keto (or any new) diet.

Because of the severe carb restrictions and elimination of food groups such as grains, the plan may also be challenging to adhere to in the long run. Trying the diet, giving it up, then trying it again may lead to weight cycling, or yo-yo dieting, which will make it harder to lose weight permanently.

If you are planning to try the keto diet, be sure to consult your healthcare team and, if possible, a registered dietitian to make sure you meet your nutritional needs on the plan. Working with a professional can help you determine whether you should make adjustments or if you’d be better off avoiding the diet entirely.

Learn More About What to Expect on the Keto Diet

Editorial Sources and Fact-Checking

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Constipation: Overview.梅奥诊所。2019年6月29日。
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Paoli A.肥胖症的生酮饮食：朋友还是敌人？International Journal of Environmental Research and Public Health。February 2014.
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Choosing Oils for Cooking: A Host of Heart-Healthy Options.哈佛医学院。March 1, 2019.
Hall KD, Guo J, Courville AB, et al. Effect of a Plant-Based, Low-Fat Diet Versus an Animal-Based, Ketogenic Diet on Ad Libitum Energy Intake.Nature Medicine。February 2021.
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Kirkpatrick CF, Bolick JP, Kris-Etherton PM, et al. Review of Current Evidence and Clinical Recommendations on the Effects of Low-Carbohydrate and Very Low Carbohydrate (Including Ketogenic) Diets for the Management of Body Weight and Other Cardiometabolic Risk Factors: A Scientific Statement from the National Lipid Association Nutrition and Lifestyle Task Force.临床脂质学杂志。September–October 2019.
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您应该尝试酮饮食吗？哈佛医学院。

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