Obesity
In simple terms, obesity can be defined as 'the excessive storage of body fat, frequently resulting in a significant impairment of health' (Wallace, 1997). It used to be considered just a 'condition' that merely leads to associated and already declared diseases; however, the World Health Organisation (WHO, 1997) now recognises obesity as a disease in its own right, and one which is largely preventable through changes in lifestyle, especially diet.

BMI Classification
There are a number of assessment methods for body fat (such as skin-folds, bioelectrical impedance and underwater weighing), but there are insufficient trials on these and a lack of standardised equations. For these reasons, Body Mass Index (BMI is the chosen form for most of the clinical standards, since it is easy to use and requires no specialist equipment.

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m²). For example, an adult who weighs 70kg and whose height is 1.75m will have a BMI of 22.9.
BMI = 70 kg / (1.75 m)²   = 70 / 3,0625   = 22.9 kg/m²

BMI values are age-independent and the same for both sexes. However, BMI may not correspond to the same degree of fatness in different populations due, in part, to different body proportions. The health risks associated with increasing BMI are continuous and the interpretation of BMI grading in relation to risk may differ for different populations.

In recent years, there was a growing debate on whether there are possible needs for developing different BMI cut-off points for different ethnic groups due to the increasing evidence that the associations between BMI, percentage of body fat, and body fat distribution differ across populations and therefore, the health risks increase below the cut-off point of 25 kg/m2 that defines overweight in the current WHO classification.

There had been two previous attempts to interpret the BMI cut-offs in Asian and Pacific populations which contributed to the growing debates. Therefore, to shed the light on this debates, WHO convened the Expert Consultation on BMI in Asian populations (Singapore, 8-11 July, 2002).

The WHO Expert Consultation5 concluded that the proportion of Asian people with a high risk of type 2 diabetes and cardiovascular disease is substantial at BMI's lower than the existing WHO cut-off point for overweight (= 25 kg/m²). However, the cut-off point for observed risk varies from 22 kg/m² to 25 kg/m² in different Asian populations and for high risk, it varies from 26 kg/m² to 31 kg/m² . The Consultation, therefore, recommended that the current WHO BMI cut-off points (as shown in table above) should be retained as the international classification.

But the cut-off points of 23, 27.5, 32.5 and 37.5 kg/mm² are to be added as points for public health action. It was, therefore, recommended that countries should use all categories (i.e. 18.5, 23, 25, 27.5, 30, 32.5 kg/m² , and in many populations, 35, 37.5, and 40 kg/m²) for reporting purposes, with a view to facilitating international comparisons.

Discussion updates
A WHO working group was formed by the WHO Expert Consultation5 and is currently undertaking a further review and assessment of available data on the relation between waist circumference and morbidity and the interaction between BMI, waist circumference, and health risk.

Press Release: February 2010
New obesity data paints a bleak future for adults

17 February 2010
Obesity trends among adults in England are continuing to increase according to an analysis by the National Heart Forum of the most recent data from the Health Survey for England. The future burden of cardiovascular disease attributable to obesity is predicted to increase substantially.
The National Heart Forum report, published today (Wednesday 17 February 2010), "A prediction of Obesity Trends for Adults and their associated diseases: Analysis from the Health Survey for England 1993-2007" is an update of the trends presented in the Foresight obesity report (2007).

The report compares previous forecasts of obesity prevalence based on Health Survey for England (HSE) data from 1993 to 2004 (published in the Foresight Report Tackling Obesities), to updated forecasts based on data from 1993 to 2007.

The team of experts, led by Professor Klim McPherson at Oxford University who is Chair of the National Heart Forum, conducted the analysis by preparing forecasts up to 2020 for overweight and obesity levels among adults using the most recent HSE data and comparing them to previous estimates, based on survey data until 2004.

The updated 2020 forecasts are in line with the forecasts made in 2007 and show no improvement in predicted trends. The updated analysis shows the predicted proportion of adults who will be obese aged 20-65 is 41% for men, and 36% for women. In the 40-65 age group, the predictions are 44% for men and 38% for women.

The predicted proportion of adults who will be overweight aged 20-65 is 40% for men and 32% for women. In the 40-65 age group, the updated predictions are that 40% of men and 32% of women will be overweight.

Importantly, the team also updated their predictions for the burdens of diseases that are attributable to obesity. Their analysis shows a substantial increase in cardiovascular diseases particularly coronary heart disease (CHD). By 2050, they predict a 23% rise in the prevalence of obesity-related stroke, a 34% rise in obesity-related hypertension, a 44% rise in obesity-related coronary heart disease and a 98% rise in obesity-related diabetes.

Commenting on the report, Professor Klim McPherson, said:
"These trends demonstrate that the cautiously optimistic picture we presented in November 2009 for a levelling off of future obesity rates among children is not mirrored in adults. There are already more men who are obese than who are of a healthy weight and by the end of the decade obese men and women could outnumber those who are overweight. The serious health problems associated with obesity mean that these continuing rising trends will impose a substantially increased burden on the NHS.

The Government needs to redouble its efforts to tackle obesity. We are being overwhelmed by the effects of today's 'obesogenic' environment, with its abundance of energy dense food and sedentary lifestyles."

Download Available:
A prediction of Obesity Trends for Adults and their associated diseases (178 Kb, pdf)

In this summary paper and its longer version companion, published on 17 February 2010, the National Heart Forum Modelling Team compare trends including the most recent data from Health Survey for England (2000- 2007) to the analysis conducted for the Foresight report for adults in three age groups. Furthermore, updated predictions for the burdens of diseases that are attributable to obesity are presented.

Download a copy of the long version: Obesity Trends for Adults:
Analysis from the Health Survey for England (402 KB, pdf)

Foresight obesity report (2007)

Research shows that in the UK obesity has trebled in the last 20 years. We are quickly becoming the most overweight population in Europe with obesity rising faster in the UK than any other European community. Obesity accounts for 2-6% of total health care costs in several developed countries; some estimates put the figure as high as 7% (WHO, 2004). The true costs are undoubtedly much greater as not all obesity-related conditions are included in the calculations. The list below shows some obesity-related conditions:

	Stroke
	Respiratory disease
	CHD
	Gall bladder disease
	Diabetes
	Osteoarthritis
	Hormonal abnormalities
	Cancer
	Hyperuricaemia and gout

Physical Effect of Obesity
Obesity is either a cause of, or is linked with, many health problems. These include diet-related non-communicable diseases, such as CHD, diabetes mellitus, hypertension, stroke, various forms of cancer (WHO, 2003), joint damage, gall bladder and respiratory problems as well as psychological problems (depression, low self-esteem).

Obesity has a direct correlation to a condition known as metabolic syndrome. The medical profession had grouped several conditions together and in 1988 called it 'syndrome X'. It has since been renamed metabolic syndrome with 6 specific health problems that tend to occur together, all of which significantly increase CHD risk.

	Central adiposity
	High cholesterol
	Hypertension
	Glucose intolerance
	Chronic inflammation
	Procoagulation

The true prevalence of metabolic syndrome is unknown but it has been estimated that 25% of the UK population show clear signs (British Nutrition Foundation, 2004).
Obesity is placing a strain upon the National Health Service with over £1/2 billion a year being directly spent on health related problems. The total cost to the economy is estimated at around £2 billion. Consequently, from a health and financial point of view, it is important to prevent where possible and treat obesity successfully.

Pathophysiology
There is not one single cause for obesity, but evidence suggests that there are many factors that lead to increased body fat. It is likely to be a number of factors that combine together rather than just one of the many factors exerting its effects.

Dietary habits (nutritional imbalance):
Dietary intake is central to weight management and therefore, will play a significant role in obesity. As the ACSM (2000) have stated, the key issue is energy balance. An excessive energy intake, in relation to energy expended, will lead to weight gain in the form of increased fat storage. This is irrespective of the type of excess energy, be in fat, carbohydrate or protein. Excess calories, regardless of the source, will ultimately be stored as fat (McArdle et al, 1996).

It is not always an excess of calories that may cause increased body fat. It is reasonably well documented that low calorie and very restrictive eating plans can initiate a starvation response in the body, which increases the body's ability to store its best energy source, fat. So in the long term it can cause weight to cycle on and off through repeated dieting and often this causes stress and nutrition deficiency, which is also harmful to health.

Much of the highly processed food available to the public today has additives and chemicals added to increase the craving response for that product, which obviously leads to more food eaten and more money made in sales. This certainly plays a part in huge increase in obesity. Many people are just falling foul of clever food science that encourages us to eat more, by simply exciting and entertaining our sensitive taste buts and palate.
Some facts about processed foods are:

	MSG Mono-sodium glutamine (MSG) and aspartame are some of the most common food additives. MSG has been widely used since the 1960's and present in most processed foods. Aspartame was sanctioned for use in 1981 and is now present in over 6000 food products. They have both been shown to cause lesions and damage to the hypothalamus which is directly responsible for the control of weight and appetite.
	Toxic If the body becomes overloaded with toxic substances, like harmful additives, it needs to protect itself and somehow safely store these toxins until the liver and kidneys are able to remove them from the body. Some experts believe that the body fat can serve as this 'safe' store for toxic substances, and if more fat is needed to store these prior to removal the body may well stimulate greater fat storage to provide for this need.
	Refined Carbohydrates Refined carbohydrates are often more appealing visually, and in many cases geared up to be more palatable. Products containing refined carbohydrates are usually very inexpensive and readily available everywhere around us. These kinds of carbohydrates can have an addictive quality as they give the struggling blood glucose a quick kick. However, they have a higher glycaemic index and therefore, deliver glucose into the system quicker. This creates a glucose overload and strains the pancreas to produce sufficient levels of insulin. Ultimately, high insulin levels are directly linked to a fat storing environment in the body.

Physical inactivity (sedentary lifestyle):
Physical activity may be one of the most important factors in the maintenance of weight loss (Wallace, 1997). Exercise early in life has been shown in studies on rats (Oscai et al, 1972) to depress the development of fat cells. Thus for the same body mass, exercised rats had been fewer adipocytes and les fat per cell. Exercise during calorie restriction diets will increase energy expenditure, slow or prevent the loss of fat-free tissue (muscle) and help maintain the resting metabolic rate (ACSM, 2000). Daily activity can account for as much as 40% or our daily calorie expenditure.

Genetics:
It is now well established that the development of obesity is linked to some extent by a variety of genetic factors (Wallace, 1997), the exact interaction of which is still the subject of continued research. Some of the main genetic issues are:

	Metabolic rate - differences occur between individuals as regards their Basal Metabolic Rate (BMR) or the number of calorie needed to just 'keep the engine ticking over'.
	Linked closely to BMR is somatotype. Clearly those who are more naturally endomorphic are more likely to gain body fat.
	Leptin is a hormone-like protein produced by fat cells, and sends messages to the brain to blunt the urge to eat. In normal situations, when the calories intake is sufficient to maintain ideal fat stores, the drive, which would lead to overeating, is suppressed. A genetic defect in either leptin production or its receptor can lead to overeating and obesity. Leptin levels have been shown to be a significant predictor of obesity and developing Metabolic Syndrome.
	Ghrelin is another hormone-like substance that is regulated in relation to eating habits. During times of energy restriction or fasting, Ghrelin levels increase, which in turn causes increased carbohydrate oxidation in preference to fat oxidation, a decrease in energy expenditure, and a general increase in fat stores. A genetic abnormality may also cause receptors and Ghrelin response to be over-stimulated.
	Gene mutation is another area where science is suggesting that there may be people who are genetically predisposed to becoming obese. Scientists have located 5 genes in mice DNA that are directly linked to obesity in mice. Although versions of these genes have been found in humans, there has been no discovery of the gene mutations seen in mice that would increase the chances of obesity in humans. Research continues in this area.
	'Set point' theory suggests that we maintain our weight when our metabolic feedback systems, tuned by our genetic make up, settle into a state of equilibrium with our environment. The many changes of culture and environment today are upsetting these equilibriums and pushing us further towards obesity.

Smoking and Alcohol:
Smoking and alcohol both have a significant influence on the body in relation to storing body fat.

	Regular smoking has been shown to increase the likelihood of abdominal weight gain by 2 fold in men and 2½ fold in women (Ha Jee et al, 2002)
	Alcohol intake of over 4 units a day was associated with increased weight gain, particularly in women under the age of 35 years old (Wannamethee et al, 2004)

Fat Distribution
Another factor to be considered is where the excess body fat is distributed. As Vega and Jimenez (2004) describe there are two types of fat distribution, android and gynoid obesity. Android obesity (apple-shaped) denotes the excess fat being stored around the abdomen. Gynoid obesity (pear-shaped) denotes the excess fat being stored on the hips and thighs. Excess fat stored near the viscera, as in android obesity, is an indicator on its own for Type II diabetes, CHD and hypertension (NIH, 2000).
Waist measurements can be used to evaluate those at high risk:

High Risk
Men	> 102 cm	( > 40 inches )
Women	> 88 cm	( > 35 inches )

Exercise Recommendations
Prescribing exercise programmes for the obese individual has to be approached with obvious caution and always with the written approval of their GP. The list of disease complications and interrelated factors could be complex. The early stages of dealing with obesity would mostly involve dietary intervention until some successful weight reduction has been achieved (ACSM, 2000). The metabolic rate of an individual who has lost 7kg (15 lbs) will be reduced by about 120 kcal/day. To maintain weight loss it is necessary for the individual to burn off any extra calories ingested with light aerobic exercise.

Clark (2004), identifies balance, stability and mobility as the key areas for obese individual. Clark quotes a study which proposed that obese individuals were at a greater risk of falls than non-obese individuals (Corbeil et al, 2001). This suggests that balance training (in and out of swimming pool; with and without stability balls) and stability work, focusing on good posture, would be of tremendous benefit to this group too.
ACSM recommendations for obesity are:

Summary of Exercise Recommendations
Warm Up		Every session	10-15 minutes	Up to Aerobic Threshold (AeT)
Main Session	Cardiovascular	Daily or 5+ x per week	20-60 minutes	Aerobic Exercise (AeT) RPE 11-13
	Resistance	2-3 x per week	1-2 sets x 15-20 Reps	8-10 exercises (circuit format, form failure)
Cool Down		Every session	10-15 minutes	Slow decrease in intensity
Flexibility		Every session	Daily or 5 x / week (hold for 10-15 seconds x 1-3) Consider Posture

Additional recommendation would be to use low impact modes of activity, because of risk of musculoskeletal wear or trauma.
Strength training may serve as a valuable companion to cardiovascular training when attempting to maintain or gain lean muscle tissue. Resistance training should focus on core, hip, knee and ankle stability, good posture and balance training.

Additional Lifestyle Recommendations

	The individual will need to improve the quality of their food and ensure their body is receiving its vital nutrients.
	Some mild calorie restriction may be employed in their diet to encourage the oxidation of body fat stores.