Naturally sourced from the leaves of a South American plant, stevia has soared in popularity over recent years.
It's free of calories and carbohydrates, and tastes around 300 times sweeter than sugar - so a little goes a long way. It's now been added to several big-brand fizzy diet drinks. You can use it in baking, too.
Any caveats? Stevia has an aniseed-like aftertaste that can be offputting. It's also pretty pricey, compared to sugar: a 270g pack of a leading stevia brand costs around £5, whereas 1kg sugar is 80p. Buy it in supermarkets and health food stores.
Another all-natural sweetener, xylitol is extracted from the fibres of a variety of plants, including berries, birch trees and corn husks. It has the look and feel of sugar, but contains 30 per cent fewer calories. Its slow absorption rate makes it a good choice for people with low glucose tolerance.
One word of warning, though: consuming too much can have a laxative effect. Xylitol is also toxic to dogs, so don't share any xylitol-based treats with your pooch. Buy it from health food stores and larger supermarkets.
Now, this one's been around a very long time - since 1879, in fact - which makes it the oldest artificial sweetener in the world. Saccharin is free of calories and carbohydrates, and around 300 to 500 times sweeter than sugar, although it does have a bitter aftertaste.
It hasn't always enjoyed a healthy reputation: during the 1970s, US research suggested a link to bladder cancer in rats. The risk to humans has since been disproved, however. Available from supermarkets.
Another artificial sweetener, aspartame is around 200 times sweeter than sugar and contains just four calories per gram. Like saccharin, it's been the subject of several well-documented health scares - but in 2013, a comprehensive European Food Safety Authority review declared it safe for human consumption, unless you have a rare genetic condition called phenylketonuria. Many people report a sweet or bitter aftertaste.
It can be bought in various forms, and is often blended with other low-calorie sweeteners. Buy it from all major supermarkets.
Derived from sucrose, this is another calorie-free artificial sweetener. But be warned: it's around 600 times sweeter than sugar, which means it's often mixed with other ingredients that aren't calorie-free in order to dilute its sweetness. In its favour, though, sucralose has no bitter aftertaste.
It does contain carbohydrates - around 0.5g per teaspoonful - but has less impact on blood glucose levels than sugar. Available from supermarkets.
This is a natural liquid sweetener derived from the agave plant, grown mainly in Mexico. It contains roughly the same amount of calories as sugar - but because it's so much sweeter, you can get away with using a third less without compromising on taste. Use it to flavour hot drinks or in baking.
One major caveat, though, is that it's high in fructose, which can trigger insulin resistance if consumed in large quantities. Available from major supermarkets.