A recent study carried out in Mexico, reinforced the concept that oxidative stress (or oxidation of the body) is present significantly in all degrees of obesity.

It is proven that obese people have lower levels of glutathione in their organisms, therefore, when their bodies are facing the battle against free radicals, the lack of energy that leads to overweight and the problems associated with obesity. Obese people are less likely to defend themselves against oxidation, as well as diseases derived from chronic overweight. Their defense mechanisms are weaker and less likely to destroy free radicals.
On the contrary, it was found that in same study, the loss of weight was directly associated with the elevation of Glutathione levels in their bodies.The metabolism process in obese people causes a low level inflammation in their fat body reserves.
Obese people usually suffer from chronic oxidative stress and this chronic nature triggers the complications of the person suffering from diabetes, for example, insulin resistance, glucose intolerance and diabetes.
Having said that antioxidant defenses in obese individuals are depleted, it is recommended that they maintain constant vigilance on their levels of Glutathione in order to fight the battle against harmful effects of obesity, highly improve their quality of life, and return to an appropriate weight.
References:
Departamento de Salud, Universidad Iberoamericana Ciudad de México. Egresada de la MaestrÃa en NutriologÃa Aplicada de la Universidad Iberoamericana Ciudad de México. México.
http://scielo.isciii.es/pdf/nh/v32n4/14originalobesidad07.pdf
Vincent HK et al. Oxidative stress and potential interventions to reduce oxidative stress in overweight and obesity.
D. Giugliano, A. Ceriello, G. Paolisso, Diabetes mellitus, hypertension, and cardiovascular disease: which role for oxidative stress? Metabolism 44 (1995) 363–368.