New research has shed light on one of the most frustrating mysteries of dieting: why the weight inevitably comes back.

According to a study by University of Michigan and the Argentina-based National Council of Science and Technology (CONICET), a study of mice demonstrated that the longer mice remain overweight, the more "irreversible" obesity becomes.

Senior author Malcolm Low said in a statement: "Our model demonstrates that obesity is in part a self-perpetuating disorder and the results further emphasise the importance of early intervention in childhood to try to prevent the condition whose effects can last a lifetime."

RealBuzz.com reveal diet tips:

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  • Friends

    While having close friends generates plenty of health benefits, research has also indicated that being overweight can be contagious amongst friends. Research results published in the journal PLoS ONE indicated that students were likelier to gain weight friends if they had friends who were heavier than them, while a study published in The New England Journal of Medicine found that having an obese friend increases your chance of obesity by 50%. The good news is being slim can also be contagious, so try to influence your social group and keep your weight down by arranging healthy, fun group activities such as walks, bike rides or dance classes.

  • Diet Foods

    You’ve cleared your cupboards of junk food, stocked up on smoothies and cereal bars, and now you’re feeling pretty saintly. However, those seemingly innocent diet foods nestling in your cupboards could actually be causing you to gain weight. Many foods claiming to be diet-friendly are actually hidden calorie traps packed with sugar and syrups. In fact, ‘healthy’ cereal bars can contain as much fat, sugar and calories as an average chocolate bar. Research by the Texas Health Science Center at San Antonio also found that those who consumed diet drinks daily experienced a 70% greater increase in waist circumference than those who drank none. Read more from <a href="http://www.realbuzz.com/articles/top-10-reasons-why-you-re-not-losing-weight">realbuzz.com</a>

  • Late Nights

    Most of us lead busy lives, and this could mean that sleep becomes a last priority. However, a study by researchers at the University of Washington found that getting less than seven hours of sleep a night was linked to a higher body weight. They also found that the longer a person sleeps, the less impact the obesity gene has on an individual’s weight. For a quick and easy way to keep off the pounds, try to skip your favourite TV show or night out every once in a while and catch up on your sleep instead.

  • To-Do List

    As well as causing you to miss out on sleep, having a hectic daily to-do list can also lead to feelings of anxiety and stress, which can quickly pile on the pounds. Cortisol – the stress hormone – not only increases your appetite, but studies have suggested that it can also affect fat distribution so that it is stored on the abdomen; leading to an unhealthy ‘apple’ shape. Furthermore, a busy lifestyle can also lead to erratic eating patterns and a reliance on unhealthy fast foods. Try to opt for healthy filling snacks instead to fuel your busy day, and make sure you take some time each day to relax and unwind.

  • Exercise

    While regular exercise is essential for good health, research has found that relying solely on exercise to manage your weight can actually be ineffective. Studies have shown that exercise, when not combined with dietary changes, does very little in respect to losing weight. Statistics also show that while obesity levels continue to grow so do the numbers of people getting active, which shows that exercise may not be having its desired effect. While exercise itself is not to blame, experts believe that many exercisers gain weight as they undo the benefits of their exercise regime by increasing their calorie intake to fuel or reward their sessions; often overcompensating for their workouts.

  • Work

    Whether you’re being tempted by staff meeting refreshments, celebrating a colleague’s birthday with cake and treats, attending business lunches or being inundated with edible gifts from grateful patients or parents, your workplace can be a source of constant food temptation, and there can be a lot of peer pressure to indulge. Furthermore, if you’re in a job that you don’t enjoy, the temptation to treat yourself is even higher. According to researchers, 62% of people break their diets mid-afternoon (with 3.23pm being the time when you are most likely to give into temptation), and this is generally due to workplace stress or boredom. Read more from <a href="http://www.realbuzz.com/articles/7-strange-tricks-that-will-help-you-to-lose-weight">realbuzz.com</a>

  • Food Sensitivities

    While few of us have serious life-threatening allergies to food, many people unknowingly suffer from intolerances and sensitivities to certain foods which can cause a wide range of vague symptoms such as stomach pain, bloating and skin problems. Shockingly, food sensitivities could also be to blame if you are struggling to lose weight. When you eat foods you are sensitive to, this triggers a reaction in the body which increases levels of insulin and cortisol; two hormones which increase fat storage, particularly around the abdomen. Furthermore, our body’s reaction to food sensitivities can also, ironically, create an addiction to the foods we are sensitive to, causing us to crave them more.

The new findings could raise questions about the long-term success rate of severe calorie restriction and strenuous exercise used later in life to lose weight.

Low says: "Somewhere along the way, if obesity is allowed to continue, the body appears to flip a switch that re-programs to a heavier set weight."

"The exact mechanisms that cause this shift are still unknown and require much further study that will help us better understand why the regaining of weight seems almost unavoidable."

The research is published in the Journal of Clinical Investigation.