“By the time you get to dinner, you’ve hit your fruit and vegetables requirements, and you’ve got most of your protein in,” Storey-Gordon says. “This allows you to have a bigger evening meal or go out with family or friends.”

Most clients settle into the 3:1 approach within a fortnight and describe it as the first eating approach that has felt sustainable, with many not even feeling like they’re on a diet, she says. As the evening is genuinely flexible – within your calorie parameters – there’s no sense of guilt or “cheating”, she adds.

Even after weight loss, it’s helpful to stick to the 3:1 way of eating, she says. “For most of my clients, what they consume to maintain their weight loss doesn’t look that different.

“Normally, they don’t change their three fixed meals, but they’ll have dessert when they go out for dinner at the weekend, or have an extra treat each day. It’s normally adding those little extras or social things back in, while the core of their diet stays the same.”

Calculate your calories

Before you dive into the 3:1 approach, you’ll need to figure out how many calories you burn per day. Storey-Gordon recommends using an online total daily energy expenditure (TDEE) calculator for this. “It’s an estimate based on your weight, height and activity level, but it will give you a ballpark figure,” she explains.

To lose weight, Storey-Gordon advises eating 20 per cent fewer calories than your TDEE. For example, if it tells you that you burn 2,000 calories per day, this would involve eating 1,600 calories.

Following this approach should lead to one to two pounds of fat loss per week, she says.

Hit the 8,000 to 15,000 step sweet spot

“I tell my clients 8,000 steps is non-negotiable,” Storey-Gordon says. If you are losing weight, she recommends adding 2,000 to 3,000 steps to your current daily average to increase the number of calories you burn.

However, there is a step-count ceiling, she notes. If you’re already getting 12,000 steps, more isn’t always better. “For most people I work with, once they get over 15,000, their appetite starts to ramp up quite a lot,” she notes.