Is sugar bad for you?
Written by Martin Ebner,
Last Updated October 2026
Sugar has become one of those ingredients people talk about as if it has evil intentions. One side treats it like poison. The other assumes a hard workout gives them unlimited access to the biscuit cupboard.
Neither position is particularly useful.
So, is sugar bad for you? In sensible amounts, no. Sugar can fit comfortably into a healthy diet, and around demanding exercise it can be genuinely useful. The important questions are how much you’re eating, where it’s coming from and whether it’s helping your body or simply adding calories you don’t need.
SUGAR AND CARBOHYDRATE AREN’T EXACTLY THE SAME THING
Carbohydrate is the wider category. It includes sugars, starches and fibre.
Your body breaks digestible carbohydrates down into smaller sugars, especially glucose, which can then be used for energy. Starchy foods such as bread, rice, pasta, oats and potatoes may not taste sweet, but much of their carbohydrate eventually becomes glucose too.
Fibre is the important exception. Your body doesn’t digest most fibre into glucose in the same way, which is one reason high-fibre foods behave differently from sweets and sugary drinks.
This doesn’t mean a potato and a packet of sweets are nutritionally identical. Food contains far more than carbohydrate. Fibre, protein, fat, water, vitamins and minerals all affect how satisfying a food is, how quickly it’s digested and what else it contributes to your diet.
WHAT YOUR BODY DOES WITH SUGAR
Once glucose reaches your bloodstream, insulin helps move it into your cells. Some is used immediately, while some is stored as glycogen in your muscles and liver for later.
That glycogen matters when you train. It helps fuel repeated muscular contractions, particularly as a workout becomes longer, harder or more demanding.
If your glycogen stores are reasonably full and your body has enough energy, the carbohydrate doesn’t somehow become dangerous. Problems are more likely when your overall calorie intake repeatedly exceeds what you use, especially when a large part of that excess comes from foods and drinks that are easy to consume without feeling particularly full.
SO, DOES SUGAR MAKE YOU FAT?
Sugar can contribute to weight gain, but it isn’t uniquely capable of making you fat.
A major systematic review and meta-analysis found that increasing sugar intake tended to increase bodyweight and reducing it tended to decrease bodyweight. However, when sugar was exchanged for the same number of calories from other carbohydrates, bodyweight didn’t meaningfully change.
The problem was the extra energy, not a special fat-producing property hidden inside sugar.
Sugary drinks are an obvious place for calories to creep upwards because you can drink a considerable amount without feeling as full as you would after eating solid food. That doesn’t make the occasional fizzy drink a disaster. It simply makes liquid calories remarkably easy to underestimate.
NATURAL SUGAR AND ADDED SUGAR
The glucose, fructose and sucrose molecules found in food don’t become virtuous because the packaging looks rustic.
Honey, maple syrup, agave and coconut sugar are still sources of free sugar. They may contain tiny amounts of other nutrients, but not enough to turn them into health foods.
Whole fruit is different because you’re getting water, fibre, vitamins and a proper piece of food alongside its naturally occurring sugar. The fibre and structure slow things down, while the volume helps you feel full.
Fruit juice loses much of that advantage. Drinking the juice from several oranges is considerably easier than sitting down and eating all of them. Juice can still fit into your diet, but it shouldn’t be treated as nutritionally identical to whole fruit.
If you’re trying to work out where added sugar is hiding, my guide to understanding food labels explains what to look for without turning a trip to the supermarket into detective work.
HOW MUCH SUGAR IS TOO MUCH?
The World Health Organization recommends keeping free sugars below 10% of your total energy intake. It suggests that reducing them below 5% may provide further benefits, particularly for dental health.
On a 2,000-calorie diet, 10% works out at roughly 50 grams of free sugar. That’s an upper limit rather than a target.
Free sugars include sugar added to foods and drinks, as well as the sugars in honey, syrups and fruit juice. The figure doesn’t include the naturally occurring sugars inside whole fruit, vegetables and milk.
You don’t need to count every gram for the rest of your life. If most of your diet comes from proper meals containing protein, fruit, vegetables, fibre and minimally processed carbohydrate, there’s room for some sugar without it taking over.
HOW MUCH CARBOHYDRATE DO YOU NEED?
There isn’t one carbohydrate target that works for everyone.
A smaller person doing three moderate strength sessions a week doesn’t need the same intake as somebody cycling for hours, running a marathon or completing two demanding sessions in one day. Your body size, total calorie needs, training volume and goals all matter.
Once you’re eating enough protein and dietary fat, carbohydrates can rise or fall according to how much work you’re asking your body to perform. The harder and more frequently you train, the more useful they tend to become.
Too much carbohydrate is the point where your total calorie intake regularly exceeds your needs, or where carbohydrate-heavy foods begin crowding protein, healthy fats, fibre and other useful nutrients out of your diet. It isn’t a fixed number that applies to everybody.
CAN SUGAR IMPROVE YOUR WORKOUT?
Absolutely, in the right circumstances.
Carbohydrate eaten before or during training can provide readily available energy and help you maintain your output. A systematic review of resistance training studies found that carbohydrate improved total training volume, with the clearest benefits during workouts lasting longer than 45 minutes and when people had fasted for at least eight hours.
That doesn’t mean everyone needs sweets before picking up a dumbbell. If you’ve eaten a decent meal and you’re doing a fairly normal session, you may already have everything you need.
The difference becomes more noticeable during long workouts, high-volume leg sessions, endurance training or when you haven’t eaten for several hours. A banana, toast with jam, yogurt with fruit or a sports drink can give a hard session a real lift without sitting heavily in your stomach.
Carbohydrate provides fuel. A pre-workout does a different job, usually supporting focus, alertness or other aspects of performance. I’ve explained what one can and can’t do in my Pre Lab Pro review.
SUGAR CAN KICK-START YOUR RECOVERY TOO
Training uses some of the glycogen stored in your muscles. Eating carbohydrate afterwards helps replenish it.
A systematic review and meta-analysis found that carbohydrate increased the rate of muscle glycogen restoration during short recovery periods. That matters most when you need to train or compete again within roughly eight hours.
If your next workout isn’t until tomorrow, you don’t need to sprint towards a bag of jelly babies the moment your final set ends. A proper meal containing carbohydrate will normally do the job.
Carbohydrate replaces fuel, while protein provides the amino acids required for muscle repair and growth. One doesn’t replace the other. My guide to protein timing for strength gains explains how the two fit together without inventing a magical 30-minute window.
WHAT ABOUT ARTIFICIAL SWEETENERS?
Approved non-sugar sweeteners aren’t automatically dangerous, but they aren’t a nutritional upgrade simply because they contain few or no calories.
Replacing a sugary drink with a low-calorie alternative can reduce your calorie intake. That may be useful if weight loss is the goal and you genuinely enjoy the replacement.
The World Health Organization’s guidance advises against relying on non-sugar sweeteners as a long-term weight-control strategy. Importantly, the guideline isn’t a claim that approved sweeteners are toxic. It’s saying that swapping one sweet product for another isn’t a substitute for improving the overall quality of your diet.
YOU DON’T NEED TO QUIT SUGAR
Sugar isn’t poison. It’s a form of carbohydrate, and carbohydrate is fuel.
Around demanding training, sugar can help you perform and recover. Away from training, it can still fit into a healthy diet without needing to be earned first. The dose, the food it arrives in and the rest of your diet matter far more than whether you occasionally eat something sweet.
I use sugar when it serves a purpose, and I enjoy it when I want it. That’s a far more sensible way to live than pretending one ingredient controls your health.
If you’ve ever wondered whether the banana before training counts as sugar, whether the sports drink was actually helping or whether dessert somehow cancelled your squats, Check It Oot is where I sort questions like that properly. One email once or twice a month, written by me, straight to your inbox.
