They key to weight loss is not what you put into your mouth, but why, US researchers have said.

With 2016 just weeks away, a lot of people will make a New Year resolution to lose weight, however many will not achieve this and among those who do, the majority will regain the weight they lose.

In fact, studies suggest that two-thirds of people who lose 5% of their total weight, gain it back, and the more weight a person loses, the lower their chances of keeping it off.

However, according to Dr Diane Robinson, a neuropsychologist at Orlando Health, these figures are not surprising as most people focus on the physical aspects of losing weight, such as diet and exercise, while ignoring the emotional aspect.

"There is an emotional component to food that the vast majority of people simply overlook and it can quickly sabotage their efforts. In order to lose weight and keep it off long-term, we need to do more than just think about what we eat, we also need to understand why we're eating," she noted.

A recent survey of over 1,000 people by Orlando Health found that 31% felt that the biggest barrier to losing weight was a lack of exercise, while 26% blamed their diet. Some 17% blamed the costs associated with maintaining a healthy lifestyle, while 12% said they did not have enough time.

Just one in 10 people felt that psychological wellbeing had a key role to play in weight loss.

"This may explain why so many of us struggle," Dr Robinson said.

She pointed out that from a very young age, people are emotionally attached to food. For example, as children, we may be given treats to console us when we are sad or reward us when we behave well. Furthermore, many annual celebrations, such as Halloween, Christmas and birthdays, are focused on food.

"If we're aware of it or not, we are conditioned to use food not only for nourishment, but for comfort. That's not a bad thing necessarily, as long as we acknowledge it and deal with it appropriately," Dr Robinson said.

She pointed out that when the brain experiences any type of pleasure, whether from food or something else, it reacts in the same way - the brain releases the neurotransmitter, dopamine, which is sometimes referred to as a ‘feel good chemical'.

"We feel good whenever that process is activated, but when we start to put food into that equation and it becomes our reward, it can have negative consequences," she said.

Studies have found a link between emotional issues, such as depression and stress, and a higher body mass index (BMI). For example, some people turn to food when they are feeling low.

Dr Robinson offers the following tips to help people recognise the emotional connection they may have to food:

-Keep a diary every day, writing down the food you eat and your mood at the time of eating. Look for unhealthy patterns
-Identify foods that make you feel good and write down why you eat them. For example, are you eating them because you feel stressed or do they evoke a certain memory
-Before you eat anything, ask yourself whether you are eating it because you are hungry. If you are not actually hungry, look for the root of your motive.

Dr Robinson said that the main aim is to view eating as providing nourishment, not as a reward or coping mechanism.

"If getting your body in shape hasn't work out yet, maybe this time start with your mind," she added.