Researchers in the United States say people who are struggling with their weight often underestimate how many calories they are actually consuming, which hinders their weight loss efforts.
Experts say the key to weight control is keeping energy intake (food) and energy output (physical activity) in balance so if only as many calories as the body needs, are consumed - weight will usually remain constant - however if a person takes in more calories than their body needs, the result will be excess fat.
Research has shown that exercise can play an important role in weight control and by increasing the energy output, more calories are used up to provide extra fuel; not only does exercise increase the metabolism during a workout, but it causes the metabolism to remain revved up for a period of time after exercising, allowing more calories to be burned off.
Therefore how much exercise is needed to make a difference in a person's weight depends on the amount and type of activity, and on how much they eat.
In a study led by Dr. Tracy Oliver, a specialist at Temple University's Center for Obesity Research and Education, the researchers found that obese women reported their activity levels most accurately, when compared to overweight and normal weight women.
By using an accelerometer, a device that measures movement and acceleration over the course of a year, the researchers were able to compare the amount of activity reported by the women to the actual amount of activity recorded.
It was found at the first measurement session and a second three months later, obese women most accurately reported the amount of physical activity they were getting - but at 12 months, all three groups were reporting on their activity levels more accurately.