Success and Failure of Dieting

• Statistics show that over the last 25 years, 22% of adults are considered obese and 75% are overweight.
• Social norms motivate people to lose weight through dieting and weightloss programmes. 
• Operant conditioning could reinforce dieting behaviour and weight loss if it is successfull. 
• Mark in 2006 argues that the reason dieting has low success rates is due to environmental and biological factors. Suggests that genetic problems such as leptin can cause failure. This is the hormone that regulates apetite. 
• To support Marks research, Havel outlined the action of leptin on various Hypothalamic areas that influence feeding behaviours. he found that leptin seemed to inhibit the release of a nueurochemical called neuropeptide Y, which stimulates hunger and eating. Therefor higher leptin levels meant that you would be less hungry. People on low calorie diets have less leptin and are therefore more hungry which could explain failure.
  
• Bellar and Jarosz in 2008 regard obesity as a complex condition and will not work by eating fewer calories. by eating so many calories over a long period of time, they have reduced the ability to cope with blood sugars. They have developed an insensitivity to insulin, as insulin regulates blood sugar levels. During a study he conducted, he found that weight loss is more succesful in the long term rather than a fast weight loss programme. 

• (supports the claim that physiological damage can result from weight loss and gain and can cause early death)  The Guardian in 2005 conducted a finish stuy in which they took 3000 overweight and obese participants and kept track of all of their weight, health and death records over a period of 24 years. It was found that those who gained and lost weight both had a higher risk of early death. 
• This study has the strengths of being longitudinal, large sample size so can be generalised. 
• This study has the weaknesses of being culturally bias and has ethical issues of confidentiality and protection of participants. 
• There is an issue with Gender in the previous approaches as most research on this topic is based on women, which is good to an extent because an increasing amount of women are becoming overweight and obese, however it affects men more due to the fat being stored around the abdomen which is near vital organs and could have more of a fatal effect. 
• There is a debate about the research being reductionist. The research is giving us useful information about how weight loss and gain can have a detremental effect on our health, however oversimplifying it can cause us to not realise how complex the subject is. 

• (Supporting the claim that psychological factors are of importance) Truby et al. in 2006 conducted a comparison study of 4 commercial diet programmes. It was completely random and had a sample of overweight and obese women who were otherwise healthy. Over 6 months, all particpants lost weight, the average being 5.9kg. One year on, the weight loss was at 10%. One diet plan was low carb, and the other was low fat. All 4 programmes gained weight loss. This goes against the leptin hypothesis. 
• This study has a strength of it being longitudinal meaning it is reliable. 
• This study has a weakness of no sample size meaning we cannot generalise to the population. 
• It also has an issue of gender again, as the study only researched women, no men. 

In conclusion, initial and quite fast weight loss is motivational to continuing a diet plan, as it provides reinforcement and rewards which is operant conditioning, however this weight loss is usually followed by the gaining of weight which could lead to severe health problems.