Governments are always telling us to eat less and exercise more to be healthier, but this presents an obvious problem.
Being active is liable to make you hungrier, so there’s a risk you end up eating extra to compensate and putting on more weight than if you’d never got off the sofa in the first place.
Dieticians dream of the day when they can design diets for people where they are more active but don’t get hungry in the process.
Unfortunately, it’s trickier than you might think: we’re still searching for the mechanism that governs how the energy we expend translates into our level of appetite. And as we shall see, that’s by no means the only thing that makes this area complicated.
In an ideal world, the human body would be wired to immediately detect changes in the amount of energy we use and then give us the appetite to eat the right amount to balance it out.
Alas not: we all get hungry two or three times a day, sometimes more, regardless of what we are getting up to.
Our bodies also release far stronger signals about our appetite when we haven’t eaten enough than when we’ve eaten too much.
This poor daily feedback relationship helps to explain why obese people still experience strong feelings of hunger – that and all the cheap calorie-dense food that is widely available, of course.
What could lie behind this difference? One possibility is that physiological processes change in people who do more exercise – for instance, their gut hormones might be released in different concentrations when they eat, potentially with a bearing on how much food they need.
One longstanding question, dating back some 60 years, is where metabolism fits into the picture. Some important work published in 2013 by a team in Leeds found that overweight people were hungrier and consumed more calories than thinner people.
Nothing can compensate for the loss of time.
They spend the rest of their lives trying to compensate for their inability to have children.