IT’S not easy to lose weight and keep it off. A bit of a cliché, I know, but I’m not sure people realise why.

One of America’s big reality TV shows years ago was The Biggest Loser – a gameshow in which a number of morbidly obese contests would compete by losing weight. It took me a while to finally get around to watching it, and when I did it was in the modern fashion of binge watching on YouTube. I was totally captivated.

It was incredible to see people, series after series, suddenly take on some of the most extreme, enduring, punishing exercise regimes I’ve ever seen, while cutting their calorie intakes to the lowest possible without risking severe malnutrition.

Seeing the weight drop from their frames week in, week out, was jaw dropping. By the end of the show, the winning contestants had slimmed down to an enviable size. The show may have been a bit crass, cruel at times, and exhibitionist, but if it was getting results like this, how bad could it be?

But then, months later, some research caught my eye. In the US, a team of people had studied the long-term effects of the programme on a number of the contestants, and the results made for grim reading.

Out of the 14 people studied, most had regained much of the weight they’d lost on the show, while only one had maintained their weight loss. This was because of their resting metabolism, it appeared: whenever someone diets, it causes their resting metabolism – the rate at which they burn calories – to fall. Our bodies go into survival mode, panicking at the loss of weight. A slower metabolism makes it harder to burn off calories, staving off further loss. It’s why people often lose lots of weight at the beginning of diets, but find it harder as they go on, even if they further reduce their calorie intake and increase their exercise output.

But in the Biggest Loser contestants, it appeared that their metabolisms did not return to normal after the show. This meant that unless they spent the rest of their lives doing notably more exercise than any other normal person they knew, and eating fewer calories a day, it would be impossible to stop the pounds climbing back on.

What all of this tells us is that our bodies actually fight against weight loss. More research is needed into exactly why and how this happens, but it explains why it’s so difficult for people to keep the pounds off once they’ve worked so hard to lose them.

That’s why I’m very much behind preventative measures when it comes to obesity. The problem, once it occurs, is incredibly difficult to fully rectify. It will likely involve a lifelong battle. But if the body never experiences obesity in the first place, it won’t keep trying to climb back up to its maximum weight.

The Scottish Government this week outlined a new strategy on diet and health, and it wants to focus on cutting childhood obesity. Action could include a crackdown on marketing promotions for unhealthy foods. The Government report described the Scottish diet as “stubbornly unhealthy”.

I realise that we’ll hear cries about the nanny state and people bemoaning the Government for taking such hands-on approaches when it comes to dealing with things like obesity, alcoholism and smoking, and it’s regrettable that some small businesses might take a financial hit, but if your business relies on profiting from the poor health of others, my sympathy starts to become limited.

In the last decade, nearly a third of adults in Scotland were classed as obese while two thirds were overweight. And when we consider how difficult it really is to lose that weight – and here’s a tip, they might not tell you that at the weekly diet classes you pay for – we begin to get a sense of how costly this problem will be for our health services in the future, particularly if we don’t prevent bad attitudes towards food becoming the norm among the nation’s children.

But there’s one key thing that can’t be forgotten: poverty and inequality. Buying fresh fruit and vegetables, with a limited shelf life, is a far more expensive prospect for those on low incomes who could buy processed foods in bulk at a cheaper price. Restricting marketing of the poorer quality foods will be no use unless healthier foods begin to look like a more affordable prospect.

A multi-layered approach is required, and there may be some trial and error, but simply trying to nudge people towards better choices when they’re contending with challenging incomes – and a selection of the finest kebab shops within a one-mile radius at any given time – isn’t going to cut it.

For children, it is deeply unfair to them. They have no concept of the change they may be inflicting upon their bodies, and the long-term battle they may have to face in order to stay healthy. In this case, Government has a duty to step in and take on the money-making culture that disadvantages citizens.