"The sugar you drink"

So far I've talked as if the tin held only biscuits and chocolate. For many people a good part of the day's sugar arrives in a cup, a can or a glass, and it does the same three jobs.

The reward is the coffee-shop drink with syrup and cream on the way back from a hard meeting. The pick-me-up is the energy drink or the can of cola at three o'clock, and the comfort is hot chocolate on a bad night. There's also sugar in the background all day, in the two spoonfuls that go into each of six cups of tea and in the glass of orange juice that feels like a healthy start.

Drinks deserve a separate mention for three reasons.

The first is that the amounts are large and easy to miss. The NHS points out that one can of cola can contain as much as nine cubes of sugar, which is more than its suggested limit for the whole day. Two sugars in each of six cups of tea is twelve spoonfuls before you've eaten anything. You'd notice if you ate twelve spoonfuls of sugar from the bowl, but in tea you don't.

The second is that fruit juice counts. People are often surprised by this, because juice comes from fruit and the sugar inside whole fruit is fine. The NHS explains that once fruit is juiced or blended, the sugars are released and count as free sugars. Its advice is to limit fruit juice and smoothies to a combined total of 150 millilitres a day, which is a small glass, and to drink it with a meal to protect your teeth. A large smoothie at your desk in the middle of the morning is, for these purposes, a sweet snack.

The third is that the evidence in chapter 5 applies with full force. Many of the studies in the Mantantzis review gave people their sugar as a drink. The finding of more tiredness and less alertness within the hour is a finding about exactly the three o'clock can. With energy drinks the picture is muddied by caffeine, which does increase alertness for a while, and which is a subject for a different book. The sugar in the can isn't what's helping.

The rule in chapter 16 treats drinks the same as food. A sweet drink with a meal, because you like it, is pudding in a glass. Between meals, the drinks that fit are water, tea and coffee without sugar, milk, and anything else unsweetened.

If you take sugar in tea or coffee, the NHS suggestion is to reduce the amount gradually until you can cut it out. Most people who've done this say the same thing. For a fortnight, tea tastes wrong. After that, tea with sugar in it tastes wrong, and they can't understand how they drank it. That matches the Monell finding in the next chapter, and it's one of the quickest places to see your own sense of taste adjust.