The ketogenic diet has seen a surge in popularity since the mid-2010s, and it can contribute to weight loss and metabolic benefits through a low-carb, high-fat approach. But where do vegetables fit in? In this article, we’ll explore what keto means, why people follow it, and which vegetables support - or sabotage - the dietary goals. Which greens make the cut, and which should you avoid? Let’s find out.
What is the Keto Diet?
The ketogenic (keto) diet is a high-fat, moderate-protein, very low-carb eating plan designed to shift your body into a state called ketosis. The body normally uses both glucose and fat for energy, but severely restricting carbohydrates increases its reliance on fat and stimulates the production of molecules called ketones, which become an important fuel source.
People often follow keto to lose weight or to stabilise blood sugar. While it can be effective, the diet is quite restrictive, eliminating many common foods like bread, pasta, sweets, and most fruits, and focusing on fats, proteins, and low-carb vegetables.
Is Keto a Recent Thing?
The lifestyle surge is relatively new, but the diet was developed in the early 1920s by Dr. Russell Wilder at the Mayo Clinic, a famous medical research organisation in the USA. The keto diet was developed as an effective treatment for drug-resistant epilepsy in children, but it gradually declined in popularity.
In the late twentieth century, fads like the Atkins Diet saw a revival of high-fat, low-carb eating, but over the last decade or so, keto has emerged as a legitimate dietary category, and has become big business, spawning a huge global industry of cookbooks, keto-friendly snacks, meal kits, and supplements.
What You Can & Can’t Eat On The Keto Diet
The main focus of the keto diet is on high-fat, moderate-protein, and very low-carb foods. You’ll typically eat plenty of meat, poultry, fish, eggs, dairy, and healthy oils like olive or avocado oil. Non-starchy vegetables can be eaten in moderation, and nuts and seeds can also fit into your daily carb allowance.
What’s off the menu, or at least what should be eaten in very small quantities? Grains (bread, pasta, rice), starchy vegetables like potatoes, butternut squash and sweetcorn, sugary snacks and drinks, most fruits, and legumes like beans, peas and lentils.
What Vegetables Can You Eat on Keto?
One of the easiest ways to think about keto-friendly veggies is ‘above-ground v. below-ground.’ Generally speaking (although there are a number of exceptions), vegetables that grow above the soil - leafy greens, brassicas, peppers, cucurbits (an interesting word we’ll explain below) - tend to be lower in carbohydrates and higher in fibre.
Some underground roots and tubers, particularly potatoes and parsnips, are relatively high in carbohydrate. Others, including celeriac, turnips and swedes, can be lower.
While there are exceptions, this rule of thumb is a useful starting point when you’re in the supermarket or planning your weekly meals.
The Good Keto Veggies
Here are some of the best keto-happy veggies to cook with when preparing meals for a keto diet.
Leafy Greens
Spinach, kale, cabbage, lettuce, Swiss chard, rocket, watercress, collard greens, and other dark, tender leaves are among the lowest-carb options available. They’re ideal for salads, and sautés, and their mild flavour also makes them easy to pair with richer, fatty ingredients like cheese, cream, or avocado.
Fungi
Although they’re technically not vegetables, mushrooms are a staple in keto cooking for good reason. Varieties such as white, shiitake, portobello, cremini, and oyster mushrooms are meaty and delicious, making them perfect for stir-fries, casseroles, or as a side to grilled meats.
Brassicas
Cauliflower, broccoli, pak choi, Brussels sprouts, and cabbage belong to this nutrient-rich family. Their firm texture holds up well to roasting, steaming, or shredding into slaws. Cauliflower, in particular, has become a keto favourite for its ability to mimic rice, mash, or even pizza bases.
Peppers
Bell peppers bring sweetness and crunch without a heavy carb load, while chillies and jalapeños add heat and complexity. They’re great stuffed with cheese and meat, tossed into fajitas, or sliced into salads.
Cucurbits
The edible parts of many cucurbits are botanically classified as fruits, but they include cucumbers, courgettes, pumpkins, squash, and even melons! Courgettes are especially versatile - think courgetti spaghetti, fritters, or baked ‘chips.’ Cucumbers are refreshing in salads or with dips, while lower-carbohydrate squashes can be used more freely than starchier varieties.
Other keto-friendly veggies include celery, asparagus, avocado (again, strictly not a vegetable), green beans, aubergine, tomatoes, radishes, endive, and okra.
The Bad Keto Veggies
Not every vegetable fits neatly into a ketogenic eating plan. The main culprits are starchy, high-carb varieties that can quickly use up your daily carb allowance and potentially knock you out of ketosis.
Root Vegetables
Potatoes, sweet potatoes, parsnips, yams, and cassava are dense in digestible carbohydrates. A single medium potato can contain 30g or more of net carbs, which may exceed an entire day’s limit for strict keto followers.
Starchy Vegetables
Some common higher-carbohydrate choices include peas, sweetcorn and pulses such as lentils, chickpeas and kidney beans, so portions usually need to be limited. Higher-carb choices include cassava, while carrots and beetroot contain more natural sugar than many leafy vegetables. Turnips and swede are generally lower in carbohydrate and may fit into a keto diet in suitable portions.
Winter Squashes
Butternut and acorn squash are generally higher in carbohydrate than summer squashes such as courgettes, so portions may need to be limited. Pumpkins vary by type and can sometimes be relatively low in carbohydrate.
Alliums & Tubers
Onions, leeks and garlic can add meaningful amounts of carbohydrate when used generously. Jerusalem artichokes are different, in that much of their carbohydrate is a fermentable fibre rather than digestible starch, although they also contain some natural sugars.
These foods are nutritious as part of a balanced diet. On keto, the higher-carbohydrate varieties may need to be limited or replaced, while others can fit into the diet in carefully chosen portions.
