According to the new survey, 67% of Brits put more weight on over the summer than during any other season, beating the Christmas and New year period to the top spot.
The average respondents revealed that they ate over 1,000 calories more at a barbecue than during a normal meal.
The study polled 2,196 adults from around the UK as part of ongoing research into the health and eating habits of British people. All respondents for the study were aged 18 and over.
Those who said that they gained weight over the summer months were asked to reveal the reasons why. 58% put this down to the amount of barbecue food they eat, whilst 34% said it was due to drinking more alcohol, such as cocktails and cider.
The researchers calculated an average response of 1,775 calories per barbecue meal. By comparison, when asked how many calories they thought they consumed during an average meal, the answer was over 1000 calories less, standing at 650 calories.
The most popular barbecue foods were: hot dogs (63%), cheeseburgers (59%) and chicken wings (54%).