What can I and can’t I eat on the keto diet?

October 3, 2020

What can you eat on the keto diet? What can’t you eat on the keto diet? And is the keto diet actually healthy?

The keto diet is a very low carbohydrate, high-fat diet that puts your body into a state of ketosis. We have busted some myths about the keto diet in previous posts, but if you still want to try it, what can you eat on the keto diet? And how much do you need to cut out?

We spoke to our expert Professor Christopher Gardner from Stanford University, to find out more. 

What is the keto diet?

The ketogenic ('keto') diet is a diet high in fat, low in carbohydrates, and with controlled protein intake that has been used since the 1920s for the treatment of epilepsy. The keto diet is an established medical treatment option for children with epilepsy that can't be controlled with medication.

It is key to recognize that ketogenic diet treatments for epilepsy should be followed with the support of an experienced dietitian who specializes in this area.

In recent years, the keto diet has increased in popularity thanks to being promoted in best-selling books, by celebrities and on social media as the solution to various ailments, substantial weight loss, and its ability to improve health. But is it all that it's hyped up to be, and does it work for everyone?

What will my diet look like on keto?

Most of us eat a diet that is composed of around 50% carbohydrates, including vegetables, fruits, grains, legumes, dairy, and refined sugars. 

To follow the keto diet, you’ll need to cut down your carbohydrate intake to less than 20g per day (which is around 5-10% of your total calorie intake). This only allows room for eating green leafy vegetables, which are low in carbohydrates, and perhaps a few berries. 

You might be picturing a daily diet of bacon and steak, but in reality, to stay ‘on keto’ and in a state of ketosis you can only eat a limited amount of protein. This is because your body can convert protein to glucose, which your cells use as fuel.

A keto diet works out at around 5% carbohydrate, 35% protein, and 60% fat. If it all sounds a bit complicated, that’s because it is. 

Restricting your carbs to this extent isn’t easy. Focusing on following the rules and staying ‘in keto’ can make your diet and your day incredibly stressful.

“All the food groups are major sources of carbs. So if you’re going to eat low-carb, what the heck are you going to eat?” Christopher says.

Enough numbers! What can I eat on the keto diet?

Following a ketogenic diet is very restrictive. The majority of foods we eat contain carbohydrates, so the list of permissible foods on a ketogenic diet is relatively short. 

Like many healthy diets, keto encourages eating non-starchy vegetables and reducing sugars and refined grains. 

But it’s important to remember that not all carbohydrates are equal (as we discussed here). So while it’s a good idea for all of us to cut down on low quality, highly processed carbs, you don’t need to get rid of every scrap of carbohydrate from your diet.

Many foods that are high in carbohydrates are also packed with healthy molecules like fiber and vitamins, as well as natural chemicals that boost our microbiome diversity and overall gut health.

Can I do keto long term and stay healthy?

Some people argue that you can get everything you need from a ketogenic diet, so the nutrients in things like starchy vegetables, fruit, and legumes are unnecessary. 

“Focusing on proteins, carbs, fats, vitamins, and minerals doesn’t capture everything we’re getting in our food,” says Christopher. 

“In most of the carb-rich, plant-based foods we eat, there are thousands of healthful phytochemicals, such polyphenols that feed the ‘good’ bacteria in your gut. If we’re trying to optimize our diets for health, vibrancy, and long life, we should include plenty of them.” 

A highly restrictive diet like keto can also be a recipe for misery. Food is an enjoyable and social part of life, so we encourage people to focus on how to eat with healthful abundance rather than deprivation and restriction.

Is the keto diet right for me?

Our PREDICT study shows that everyone responds to carbohydrates in their own way

If you’re someone who has healthy responses to carbohydrates and unhealthy responses to fat, following a low carb high fat (LCHF) diet like keto may be setting you up for health problems down the road.

Our PREDICT study showed that unhealthy fat responses after eating are strongly linked with a rise in biological markers of inflammation (dietary inflammation), which may increase the risk of heart disease. 

Beyond the potential health aspects of following keto, you also need to think about whether you can stick to it. 

“Keto is a very restrictive diet, so a lot of people lose weight fast on it because very few things are allowed,” says Christopher. “So you’re eating less, and you’re losing weight, but can you do it forever? The reality is that restrictive diets don’t work for most people in the long term.”

Actionable insights, tailored to your biology

We believe that understanding how your body works is key to picking the right foods for you. Our at-home test kit lets you discover your metabolic responses to carbohydrates and fats, along with personalized advice about the food choices that will work with your metabolism and microbiome to reduce dietary inflammation and improve your gut health. Ready to get biology on your side?


The keto diet in a nutshell:

  • The keto diet focuses on eating meat, fats, and non-starchy veggies
  • All other vegetables, fruit, legumes, whole grains, refined grains, and sugary foods are not allowed
  • The diet does aid weight-loss for some people, but not for others
  • Following a keto diet is a very restrictive way to eat and might be problematic in the long-term
  • Right now, we don’t know the full health implications of cutting out plant-based carbohydrates and fiber from our diets 
  • The keto diet is a restrictive low carbohydrate diet
  • The diet represents a drastic change from the standard American diet, which is about 50% carbohydrate
  • If you follow the diet, you can expect to eat a lot of fats, a moderate amount of protein, leafy green veg, and a few berries
  • The diet can be challenging to stick to long term because it is so restrictive
  • The lack of fiber and plant-based foods may be detrimental to your microbiome and overall health 

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