A poll of 2,000 adults found more than a fifth (23%) weigh more than a year ago, while 58% believe the financial crisis has contributed to their weight gain.
And 31% prioritize the cost of food over its health.
In fact, 18% said they do more unhealthy food swaps now than they did before the Cost of life crisis started.
Since the end of 2021, 80% of adults said they were concerned about rising food prices.
Dr Jacquie Lavin, Special Advisor on the Science of Weight Management at Slimming World, said: “It’s well documented that the cost of living crisis is having a big impact on people’s shopping habits.
“This research shows that 31% of people prioritize the cost of food over their health.
“Without the right support, there is a very real possibility that the financial crisis will make it even more difficult for people to manage their weight and their health.”
The survey found that of those who gained weight, 38% attributed it to the comfort of eating or eating more fast food.
The cost of living impact also led 30% to say they are less motivated to exercise and 20% to use alcohol to cope with the stress of the situation.
Just under a fifth (19%) have changed where they shop due to the rising cost of living.
It’s not just physical health that has been affected in recent months, as 46% say their mental well-being has also taken a hit.
And 47% believe the government is not doing enough to help people eat healthy foods as the country’s finances are stretched.
The survey, carried out by OnePoll, found that 68% believe it’s easier to be healthy when you have plenty of money.
Dr Lavin, for Slimming World, said: “Getting practical advice and proven, tangible tips can be especially helpful when you’re having more trouble eating healthy and losing weight or staying on track.
“Research has shown that around 38% of UK adults do not feel they have received advice, for example from friends and family, social media, supermarkets or colleagues.
“It shows how much being part of a group, where we face the same challenges together and where we help each other to stay motivated, makes a real difference. It’s even better when this support is offered in a warm and friendly community, especially during these difficult times. »