Diet guide
Low-carb diets, explained
Low carb can mean anything from dropping fizzy drinks to cutting out bread and fruit entirely. Here's how to pick a level that suits you and fill your plate so you're not hungry.
Most people call a diet low carb when it has under about 130 g of carbs a day, and very low carb under about 50 g. How well it works for you depends on how far you go, what you eat instead, and whether you can keep it up. Swapping white bread for vegetables and beans does a lot more good than swapping it for sausages.
What counts as low carb
There's no single low-carb diet. Atkins, South Beach and keto all sit under the label, and so does simply cutting back on toast and biscuits.
For context, the usual guideline is that 45-65% of your calories come from carbohydrate. On a 2,000-calorie day that's roughly 225-325 g. So a lot of people are eating 250 g or more without thinking about it. A can of regular cola alone has about 35-39 g of sugar, depending on the size.
The lower you go, the more foods drop out and the more planning it takes. At the very bottom is the keto diet, where the aim is to get your body into ketosis.
Pick your level: moderate, low or very low
If you're starting from a typical diet, moderate is a sensible first step. Many people get most of the benefit there: fewer blood sugar crashes, fewer snacks, and easier weight loss, without giving up foods they love. The glycemic index can help you choose which carbs to keep.
What to eat instead: a sample day
What replaces the carbs matters more than the carb number itself. That's one of the most consistent findings in the research. Cut white bread and eat more vegetables, beans, nuts, fish and olive oil, and your heart health tends to improve. Cut white bread and eat more bacon, salami and butter, and it may not.
Here is what a day at around 80-110 g of carbs might look like:
- Breakfast: plain Greek yogurt with a handful of blueberries and some walnuts. Or two eggs on one slice of wholegrain toast with sliced tomato.
- Lunch: a big salad with tuna or chicken, a few spoonfuls of chickpeas, cucumber, peppers, olives and an olive oil dressing. An apple on the side.
- Snack: hummus with carrot and pepper sticks, or a small handful of nuts.
- Dinner: a chicken or tofu stir-fry with lots of vegetables and half a cup of brown rice, instead of the usual full plate.
Swaps that make a big difference:
- Fizzy drinks and juice for water, sparkling water or unsweetened tea.
- A sandwich for the same filling on a salad, or in one slice of bread instead of two.
- Half your usual rice or pasta, with the other half of the plate as vegetables.
Cutting added sugar first is the easy win. The WHO suggests keeping it under 10% of your calories, ideally under 5%.
The first two weeks, and how to tell it's working
Week one: the scale often drops a couple of pounds quickly. Most of that is water, because stored carbohydrate holds water with it. If you went very low, you might feel tired, headachy or foggy for a few days. Extra water and a little more salt usually help.
Week two: cravings for sugar often start to fade. Many people notice they're less hungry between meals and don't get the 3pm slump after lunch. Constipation is common if you've dropped bread and cereal without adding vegetables, beans or seeds.
After a month, it's working if:
- you're losing about 0.5-1 kg (1-2 lb) a week, or your clothes fit better;
- you're snacking less and not white-knuckling your way to dinner;
- it doesn't feel like a fight at every meal.
Over six months to a year, studies tend to find that low-carb and low-fat diets lead to similar weight loss when people eat a similar number of calories. It comes down to which one you can stick to. If you have type 2 diabetes, low carb can bring blood sugar down, which is good, but it's also why medication may need adjusting.
Common mistakes
- Making processed meat the main event. Bacon, ham and salami every day aren't good for your heart or bowel. Keep them occasional.
- Losing fibre. When bread and cereal go, fibre goes with them. Replace it with vegetables, beans, lentils, nuts, seeds and berries.
- Cutting too hard, too fast. Going from 300 g to 20 g overnight is how people end up miserable and quit in week two.
- Trusting "low carb" labels. Low-carb bars, breads and desserts are often expensive and highly processed. Check the net carbs claim too, since the term isn't regulated in the US.
- Forgetting calories still count. Cheese, nuts and oil are healthy in sensible amounts but easy to overeat. A calorie deficit is still what drives weight loss.
How to start, and how to ease off
Before you start, ask yourself a few honest questions. How low do you actually need to go? What will you eat at work and at family meals? Does it fit your training, your culture and your budget? And what's the plan in three months?
A simple start: for two weeks, just cut sugary drinks, sweets and pastries and halve your portions of bread, rice and pasta. See how you feel. Only go lower if you want to and it's going well.
If you went very low and want to ease off, add back about 10-15 g of carbs a day each week. Start with beans, lentils, whole fruit, oats and potatoes rather than white bread and sweets. Expect a small, quick gain on the scale as water comes back. That isn't fat. Many people settle at the moderate level for good, or move toward a Mediterranean diet, which keeps whole grains and beans. If you're unsure how long to give it, see how long you should try a diet.
Check with a doctor first if this is you
- You use insulin or diabetes tablets like gliclazide or other sulfonylureas. Cutting carbs can cause low blood sugar within days, so doses often need to change.
- You take blood pressure medication. Low-carb eating can lower blood pressure too.
- You're pregnant or breastfeeding. Carbs from fruit, whole grains and beans help you get enough fibre and folate.
- You have kidney, liver, pancreas or gallbladder problems.
- You have or have had an eating disorder.
- It's for a child or teenager.
Unsure? See do I need a dietitian to start?
Who low carb suits, and who it doesn't
| Situation | What it means for you |
|---|---|
| Likely a good fit | You snack on sweets, drink sugary drinks or eat big portions of bread and pasta, you get energy crashes after carb-heavy meals, or you prefer to cut foods rather than count calories. |
| Stay at the moderate end | You're vegetarian, you do a lot of endurance or team sport, or you cook for a family. Keep beans, fruit and some whole grains. |
| Probably a poor fit | Your diet is built around rice, roti, pasta or beans and you'd miss them badly, or you've found strict food rules lead you to binge. |
| Get individual advice | You're on insulin, sulfonylureas or blood pressure pills, you're pregnant or breastfeeding, or you have kidney, liver, pancreas or gallbladder disease. |
Low-carb questions people ask
How many carbs a day is considered low carb?
Usually under about 130 g a day. Many plans aim for 50-100 g, and under about 50 g is very low carb, close to or at keto. A moderate cut to 100-150 g is where most people start.
Is low carb the same as keto?
No. Keto is the strictest version, usually 20-50 g a day, aimed at ketosis. Most low-carb eating is less strict and still includes some fruit, beans and whole grains.
What can I eat on a low-carb diet?
Meat, fish, eggs, dairy, tofu, nuts, seeds, olive oil and plenty of vegetables, plus some fruit, beans and whole grains depending on your level. Cut sugary drinks, sweets, white bread and large portions of rice, pasta and potatoes first.
Will I lose weight faster on low carb?
At first, yes, mostly from water. Over six to twelve months, weight loss is usually similar to other diets with the same calories. What matters most is which one you can keep doing.
Is a low-carb diet good for type 2 diabetes?
It can lower blood sugar and is one reasonable option. But if you take insulin or sulfonylureas, talk to your doctor before you start, because your medication may need to change quickly.
Sources
If you take medicine for diabetes or blood pressure, are pregnant, have kidney, liver or gallbladder problems, or have had an eating disorder, check with your doctor or a dietitian before cutting carbs sharply. Medication doses can need changing within the first week.