A low-carb diet limits carbohydrates to roughly 60 to 130 grams per day, compared to the 200 to 300 grams most people eat. The basic idea is simple: you replace starchy and sugary foods with proteins, healthy fats, and non-starchy vegetables. The exact threshold varies depending on which approach you follow, but any eating pattern that deliberately restricts carbs below typical intake falls under the low-carb umbrella.
How Many Grams Count as Low Carb
There’s no single cutoff, but the general range breaks into two tiers. A standard low-carb diet allows 60 to 130 grams of carbohydrates per day. A very-low-carb diet drops below 60 grams, which works out to roughly 240 calories from carbs. For context, a single medium bagel contains about 50 grams of carbohydrates on its own.
The ketogenic diet is the most restrictive mainstream version, typically limiting carbs to under 50 grams per day and sometimes as low as 20 grams. At that level, the body shifts into ketosis, burning fat for fuel instead of glucose. Not everyone on a low-carb diet is aiming for ketosis. Many people find meaningful results in the 80 to 130 gram range without going that far.
What Happens in Your Body
Carbohydrates break down into glucose, which triggers your pancreas to release insulin. Insulin’s job is to shuttle that glucose into your cells for energy and store any excess. When you eat fewer carbs, your blood sugar rises less after meals, and your body produces less insulin in response. With lower insulin levels, your body shifts toward burning stored fat for energy more readily.
This mechanism is especially relevant for people with type 2 diabetes. Research from the Endocrine Society found that people with type 2 diabetes who followed a low-carb diet saw improvements in their insulin-producing cells that were twofold greater than those on a high-carb diet. Over time, their pancreas became better at responding to blood sugar, and some participants were able to reduce their medications.
What You Eat on a Low-Carb Diet
The foundation of low-carb eating is non-starchy vegetables, proteins, and fats. Non-starchy vegetables are remarkably low in carbs: a half-cup of cooked broccoli, cauliflower, green beans, peppers, or zucchini contains only about 5 grams. Salad greens like lettuce, spinach, and arugula are so low they’re essentially free. You can eat large volumes of these without putting a dent in your daily carb count.
Fruit fits into a low-carb diet in smaller portions. A cup and a quarter of whole strawberries has about 15 grams of carbs. So does three-quarters of a cup of blueberries, a small apple, or 17 grapes. Berries tend to be the most low-carb-friendly fruits because you get a decent serving size for relatively few grams. Bananas, dried fruit, and fruit juice are higher in carbs and harder to fit in.
Proteins like meat, fish, eggs, and cheese contain little to no carbohydrate. Fats from olive oil, avocado, nuts, and butter are also essentially zero-carb. These become the caloric backbone of the diet, replacing the energy you would have gotten from bread, pasta, rice, and potatoes.
How to Calculate Net Carbs
Many people on low-carb diets track “net carbs” rather than total carbs. The idea is that fiber passes through your body without raising blood sugar, so it shouldn’t count against your limit. To get net carbs, you subtract the grams of fiber from the total carbohydrate count on a nutrition label.
Sugar alcohols, common in low-carb packaged foods, are a bit different. Your body absorbs roughly half of them. The UCSF Diabetes Teaching Center recommends subtracting half the grams of sugar alcohol from the total carbohydrate count. So if a protein bar lists 29 grams of total carbs and 18 grams of sugar alcohols, you’d subtract 9 grams (half of 18) and count it as 20 grams of net carbs.
Short-Term Side Effects
Cutting carbs sharply, especially below 50 grams per day, often triggers a cluster of symptoms sometimes called “keto flu.” This is essentially carbohydrate withdrawal as your body adapts to using fat for fuel. Common symptoms include headaches, brain fog, irritability, muscle soreness, sugar cravings, nausea, and trouble sleeping.
These symptoms typically start within the first day or two. For most people, they resolve within a week. In more extreme cases, the adjustment period can stretch to about a month. Staying hydrated and keeping up your electrolyte intake (sodium, potassium, magnesium) helps ease the transition. A more gradual reduction in carbs, rather than dropping to 20 grams overnight, can also soften the adjustment.
Who Should Be Cautious
Low-carb diets are generally safe for healthy adults, but certain groups face real risks. People with diabetes who take blood sugar-lowering medications can experience dangerously low blood sugar if their medication isn’t adjusted to match their reduced carb intake. This is a medication timing issue, not a problem with the diet itself, but it requires medical coordination.
Ketogenic diets specifically are not recommended during pregnancy, as their safety hasn’t been established and animal studies show mixed results on fetal development. People with kidney stones, significant liver disease, or certain inherited metabolic conditions should also avoid very-low-carb approaches. As carbohydrate intake decreases, the risk of nutrient deficiencies increases, particularly for B vitamins, fiber, and certain minerals that are abundant in whole grains and fruits.
Choosing Your Level of Restriction
You don’t have to go full keto to benefit from reducing carbs. Someone eating 250 grams of carbs per day who drops to 130 grams has made a significant change. They’ve cut out a lot of refined sugar and processed starch while still eating fruit, some whole grains, and a wide variety of vegetables without much tracking.
Dropping to the 50 to 60 gram range requires more planning and eliminates most grains, starchy vegetables, and all but small servings of fruit. Going below 20 grams is the most restrictive approach and demands careful attention to every ingredient. The right level depends on your goals, your health situation, and what you can sustain over months rather than days. A moderate low-carb approach that you actually stick with will always outperform a strict one you abandon after two weeks.