Weight loss, in the context of medicine or health or physical fitness,is a reduction of the total body weight, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bones mineral deposits, muscle, tendon and other connective tissue. Physical fitness is the functioning of the heart, blood vessels, lungs, and muscles to function at optimum efficiency. In previous years, fitness was defined as the capacity to carry out the days activities without undue fatigue.

Automation increased leisure time, and changes in lifestyles following the industrial revolution meant this criterion was no longer sufficient. Optimum efficiency is the key. Physical fitness is now defined as the body as ability to function efficiently and effectively in work and leisure activities, to be healthy, to resist hypo kinetic diseases, and to meet emergency situations. Fitness can also be divided into five categories: aerobic fitness, muscular strength, muscular endurance, flexibility, and body composition.

There is a substantial market for products which promise to make weight loss easier, quicker, cheaper, more reliable, or less painful. These include books, CDs, cremes, lotions, pills, rings and earrings, body wraps, body belts and other materials, not to mention fitness centers, personal coaches, weight loss groups, and food products and supplements. US residents in 1992 spent an estimated $30 billion a year on all types of diet programs and products, including diet foods and drinks

The revised NCEP and IDF definitions of metabolic syndrome are very similar and it can be expected that they will identify many of the same individuals as having metabolic syndrome. The two differences are that IDF excludes any subject without increased waist circumference, while in the NCEP definition metabolic syndrome can be diagnosed based on other criteria and the IDF uses geography-specific cut points for waist circumference, while NCEP uses only one set of cut points for waist circumference regardless of geography. These two definitions are much closer to each other than the original NCEP and WHO definitions.

Like most atypical antipsychotics, compared to the older typical ones, olanzapine has a lower affinity for histamine, cholinergic muscarinic and alpha adrenergic receptors. The mode of action of olanzapine's antipsychotic activity is unknown.It may involve antagonism at serotonin receptors.Antagonism of dopamine receptors is associated with extrapyramidal effects such as tardive dyskinesia, and with therapeutic effects.

As with all neuroleptic drugs, olanzapine can cause tardive dyskinesia and rare, but life-threatening, neuroleptic malignant syndrome.Other recognised side effects may include: akathisia inability to remain still, dry mouth, dizziness, sedation, insomnia, Urinary Retention inability to pass urine, can lead to cathterisation if treatment isn't stopped, weight gain (90% of users experience weight gain)(see below).The results of a large, random-design study funded by NIH's National Institute of Mental Health were published in September 2005. The 18-month study, which involved 1,400 participants at 57 sites around the country, found that patients on olanzapine also experienced substantially more weight gain and metabolic changes associated with an increased risk of diabetes than those participants taking the other drugs.

However, the study also found that olanzapine helped more patients control symptoms for significantly longer than the other drugs.Specifically, after 18 months, the researchers found, 64 percent of the patients taking olanzapine had stopped, while at least 74 percent had quit each of the other medications.