"I'm addicted to sugar"

Many people with a daily habit like this describe themselves as sugar addicts. Magazines and documentaries encourage it. You may have read that sugar lights up the same parts of the brain as cocaine, and that rats prefer it to drugs.

It matters whether this is true, for a practical reason. If you believe you're addicted, you'll expect change to involve withdrawal, cravings you can't resist and a lifetime of vigilance. You'll also believe that the only real option is to give sugar up completely, which you don't want to do, so you'll do nothing.

Margaret Westwater, Paul Fletcher and Hisham Ziauddeen, researchers at Cambridge, reviewed the evidence on sugar addiction in 2016. They set what's known about drug addiction alongside what's been found for sugar, in animals and in people. Their conclusion was that there's little evidence to support sugar addiction in humans. People don't develop tolerance to sugar in the way they do to a drug, and they don't go through a withdrawal syndrome when they stop eating it.

The rat studies you may have read about are real, and the review explains what they show. Rats did develop something that looked like bingeing on sugar. But it happened only when the animals were given sugar on a restricted schedule, with access for a limited period each day after hours of going without. Rats with sugar freely available didn't binge on it. The reviewers concluded that the addiction-like behaviour came from the on-and-off access to a very palatable food, and not from any chemical action of sugar on the brain.

I find that detail interesting for a reason beyond rats, and this is my interpretation. The pattern that produced bingeing was deprivation followed by access. That's the pattern a person sets up when they swear off sugar entirely on Monday, hold out until Thursday, and then open the tin. If strict bans followed by collapses are part of your history, the bans may have been feeding the problem. It's one reason this book doesn't ask you to ban anything.

As for the brain scans, pleasant things do activate the brain's reward circuits. That's what those circuits are for. Music does it, and so does a smile from someone you like or a win for your football team. Showing that sugar does it too shows that sugar is pleasant, which nobody doubted.

So what is going on, if it isn't addiction? I think it's two ordinary things working together. The first is a genuine liking for sweetness, which you were born with. The second is habit, in the plain sense. You've eaten a biscuit with your eleven o'clock tea so many times that the kettle going on calls up the biscuit without your deciding anything. The slump at three calls up the drawer, and a bad phone call calls up the tin. Those links are strong because they've been rehearsed thousands of times, and because the tin is always within reach. A strong habit like that can still be broken.

I don't want to minimise how hard a pull can feel. When you've just put the phone down on your sister, the wanting is real and physical. But the wanting comes from a cue and a memory, and those fade when they stop being rehearsed. It doesn't come from a body in chemical need, and you won't go through withdrawal. If you stopped using sugar for its three jobs tomorrow, the worst you'd face is a few weeks of reaching for something that isn't there, the way you reach for a light switch in a house you've moved out of.