Looking to lose weight? Keto is one of the biggest diet fads out there today. But first, learn what you can and can’t eat with this comprehensive food list and meal plan.

If you’re looking to get a jump start on your health and fitness goals this year, you may be thinking about trying the ketogenic diet. Maybe you’ve heard the phrase before — it’s a huge diet buzzword — but aren’t sure what it means. Here’s a primer: The ketogenic diet is an eating plan that drives your body into ketosis, a state where the body uses fat as a primary fuel source (instead of carbohydrates), says Stacey Mattinson, RDN, who is based in Austin, Texas.


When you’re eating the foods that get you there (more on that in a minute), your body can enter a state of ketosis in one to three days, she adds. During the diet, the majority of calories you consume come from fat, with a little protein and very little carbohydrates. Ketosis also happens if you eat a very low-calorie diet — think doctor-supervised, medically recommended diets of 600 to 800 total calories per day.

Benefits and Risks of the Diet That Beginners Need to Know

Before you dive in, it's key to know the possible benefits and risks of keto.

Research backs up undertaking a ketogenic diet in three circumstances: to aid treatment of epilepsy, to help manage type 2 diabetes, and to support weight loss, says Mattinson, and the last two purposes still need more studies. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.

But for people with diabetes, one big concern is you're eating a lot of fat on keto, and that fat may be saturated, which is unhealthy when eaten in excess. (The much higher total fat intake is also a challenge among keto beginners.)

Because people with type 2 diabetes are at an increased risk for cardiovascular disease, there’s a specific concern that the saturated fat in the diet may drive up LDL, or “bad,” cholesterol levels, and further increase the odds of heart problems. If you have type 2 diabetes, talk to your doctor before attempting a ketogenic diet. She may recommend a different weight loss diet for you, like a reduced-calorie diet, to manage diabetes. Those with epilepsy should also consult their doctor before using this as part of their treatment plan.

The keto diet may also help improve short- and long-term cognition among people who are living with Alzheimer’s disease and are experiencing mild cognitive impairment, according to a systematic review of randomized controlled trials that was published in Advances in Nutrition in June 2020. right up arrow Researchers caution that further research is needed to confirm these findings and prove a cause-and-effect relationship between keto and preventing dementia.

In terms of weight loss, you may be interested in trying the ketogenic diet because you’ve heard that it can make a big impact right away. And that may be true. “Ketogenic diets will cause you to lose weight within the first week,” says Mattinson. She explains that your body will first use up all its glycogen stores (the storage form of carbohydrate). With depleted glycogen, you’ll drop water weight. While it can be motivating to see the number on the scale go down (often dramatically), do keep in mind that most of this is water loss initially.

But the keto diet can be an effective option over time. One review suggested the keto diet can spur fat loss in obese people when used for a couple of weeks and up to one year. right up arrow A meta-analysis noted that one likely reason for weight loss is that keto diets may suppress hunger. right up arrow
One downside to the ketogenic diet for weight loss is that it's difficult to maintain. “Studies show that weight loss results from being on a low-carb diet for more than 12 months tend to be the same as being on a normal, healthy diet,” says Mattinson. While you may be eating more satiating fats (like peanut butter, regular butter, or avocado), you’re also way more limited in what’s allowed on the diet, which can make everyday situations, like eating dinner with family or going out with friends, far more difficult. Because people often find it tough to sustain, it’s easy to rely on it as a short-term diet rather than a long-term lifestyle.

Another potential downside to the keto diet: the keto flu. One study, published in March 2020 in Frontiers in Nutrition, right up arrow found that across 43 different online forums for people following a keto diet, about a third of commenters reported experiencing this short-term keto side effect. In the first few days after you begin your keto diet plan, you may experience headaches, muscle cramps, fatigue, nausea, constipation, and other flu-like symptoms, according to Harvard Health Publishing. right up arrow These symptoms usually resolve within a few days to a few weeks, and you can help to counter them by drinking plenty of fluids with electrolytes, according to an article published June 2020 in StatPearls. right up arrow
Before starting, ask yourself what is really realistic for you, Mattinson suggests. Then get your doctor’s okay. You may also work with a local registered dietitian nutritionist to limit potential nutrient deficiencies and talk about vitamin supplementation, as you won’t be eating whole grains, dairy, or fruit, and will eliminate many veggies. “A diet that eliminates entire food groups is a red flag to me. This isn’t something to take lightly or dive into headfirst with no medical supervision,” she says.

What to Keep in Mind When Creating Your Ketogenic Meal Plan

If you’ve decided to move forward in trying the keto diet, you will want to stick to the parameters of the eating plan. Roughly 60 to 80 percent of your calories will come from fats. That means you’ll eat meats, fats, and oils, and a very limited amount of nonstarchy vegetables, she says. (This is different from a traditional low-carb diet, as even fewer carbs are allowed on the keto diet.)

The remaining calories in the keto diet come from protein — about 1 gram (g) per kilogram of body weight, so a 140-pound woman would need about 64 g of protein total. As for carbs: “Every body is different, but most people maintain ketosis with between 20 and 50 g of net carbs per day,” says Mattinson. Total carbohydrates minus fiber equals net carbs, she explains.

One thing to remember: “It’s easy to get ‘kicked out’ of ketosis,” says Mattinson. Meaning, if you eat something as small as a serving of blueberries, your body could revert to burning carbohydrates for fuel rather than fat.


A Complete Food Guide to Follow

Wondering what fits into a keto diet — and what doesn’t? “It’s so important to know what foods you’ll be eating before you start, and how to incorporate more fats into your diet,” says Kristen Mancinelli, RD, author of The Ketogenic Diet: A Scientifically Proven Approach to Fast, Healthy Weight Loss, who is based in New York City. We asked her for some guidelines.

Protein

Liberally Ketogenic diets aren’t high in protein (they focus on fat) so these should all be consumed in moderation.

  • Grass-fed beef
  • Fish, especially fatty fish, like salmon
  • Dark meat chicken

Occasionally
  • Bacon
  • Low-fat proteins, like skinless chicken breast and shrimp. These are great to include in your keto diet, but add a sauce on top for some fat rather than eating them plain.

  • Never

    • Cold cuts with added sugar (read the label!)
    • Meat that has been marinated in sugary sauces
    • Fish or chicken nuggets

    Oil and Fat

    Liberally

    • Avocado oil
    • Olive oil
    • Coconut oil
    • Butter
    • Heavy cream

    Occasionally Limit your consumption of these oils, which should be easy to do if you're avoiding packaged foods, where they're often found.

    • Sunflower oil
    • Safflower oil
    • Corn oil

    Never

    • Margarine
    • Artificial trans fats

  • Fruits and Veggies

    Liberally

    • Avocado
    • Leafy greens, like spinach and arugula
    • Celery
    • Asparagus

    Occasionally These are great choices, but you’ll need to count the carbs.

    • Leeks
    • Spaghetti squash
    • Eggplant