More than 100 reasons which are responsible for making losing weight so difficult for people have been revealed by researchers.
Experts say that everything from using a remote control to change TV channels to having the wrong sort of friends can help us gain weight.
Other things to be taken into account include our genes and the temptation to drive, rather than walk, short distances.
According to the British Nutrition Foundation, though some factors, such as our genes, can't be altered, there are many small changes that can be made and which together can have a big impact on weight.
The charity has used a list of 108 things affecting our weight, compiled for a Government report, as a starting point for its advice.
The 'fat factors' have been divided into seven groups - social, psychological, eating and drinking, physical activity, our environment, physiology, and TV, computers and magazines.
Having the wrong sort of friends falls into the first category. While they may be good fun, they could also be encouraging us to eat the wrong things or tease us when we speak about wanting to exercise or join a gym.
Snacking when bored and treating food as something as reward when things go well both fall into the category of psychological pressures.
Gulping down food can mean that we eat too much before the body's satiety signals kick in, while using TV remote controls can make our lifestyle particularly sedentary.
People are also bombarded by TV adverts for unhealthy foods and many of us don't even take adequate sleep.
But there are many adjustments that we can make to our lifestyles to improve our chances of shedding the pounds.
In its Small Changes: Big Gains guide, the British Nutrition Foundation has made suggestions such as getting up from the TV and doing some housework during advert breaks.
This could burn 40 calories per hour of TV viewing.
Hiding the remote control and instead changing channels manually would use up another 15 calories an hour.
Measuring out small portions of crisps, instead of eating them straight from the bag, could save us 130 calories, while office workers who get up to talk to a colleague or make a drink at least once an hour can burn off around 120 more calories per day.
Even fidgeting has its benefits, with someone who taps their feet while sitting burning up to 350 calories a day more than someone who stays completely still.
To put the figures in context, a glass of wine contains around 90 calories and a bar of chocolate around 180.
"There are lots of different options to choose from in terms of making changes in our behaviour that could have a positive impact on health.' Miss Benelam said the key to losing weight could be to try to make at least one change within each of the seven groups," the Daily Mail quoted Senior nutrition scientist Bridget Benelam as saying.
"Within each of these categories there are multiple influencers and we believe that by proactively selecting a range of these to focus attention on, people can make a series of small changes to their behaviour which, when combined, will have a larger overall effect.
"For example, we believe that social engagement can have a positive impact on weight management for some people, as can developing cooking skills, keeping a food or activity diary, spending more time outside, and using the same weekly on-line grocery shopping list," she added.