Advanced Biology Presentation

Weight Control and Obesity

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Obesity action plan  

Doctors have called for heavier taxes on fizzy drinks and a ban on pre-watershed adverts for junk food, in a bid to

combat Britain’s “obesity epidemic”. Other proposals in the report by the Academy of Medical Royal Colleges

(AoMRC) include a ban on new fast-food outlets near schools and colleges, mandatory food standards in hospitals, and a £100m annual budget for anti-obesity measures such as weight-loss surgery. The AoMRC said the issue was “the

biggest public health crisis facing the UK today”.This country has the highest rate of obesity in Europe; if current

trends continue, half of British children will be obese or overweight by 2020.

It would be very easy to cure Britain’s obesity epidemic, says Minette Marrin. All we have to do is accept that sugar is “as good as bad poison and should be avoided”. The stuff isn’t just fattening but addictive; it messes with your metabolism. And it is present to an alarming degree in almost all processed foods, and fizzy drinks in particular. As one distinguished doctor says of these drinks: “You’re just consuming neat sugar. Your body didn’t evolve to handle this kind of thing.” What’s needed is a legislative crackdown on sugar-laden food and drinks. The rise in obesity, which threatens to cripple the NHS, can’t just be put down to gluttony. It is in large part something that is being inflicted on people. “It should be stopped, or rather the Government should stop it.”   The Sunday Times

Britain gets bigger  

New NHS figures revealing Britain’s obesity epidemic make for dismaying reading: a tenth of children are now

obese when they start school, and by the time they are 11, the proportion has doubled to one in five. The figures are

similar to last year’s, suggesting that the trend is “flattening out” among children. But adults may still be upsizing, reports The Guardian. Only one in three men are now

considered a normal weight for their height (down from 41% in 1993); the proportion of women with a healthy BMI

has fallen from 50% to 39%. The figures also reveal that only a third of adults manage 30 minutes of physical

activity at least once a week, and that the number of people admitted to hospital with a primary diagnosis of obesity

tripled between 2006-7 and 2011-12, to 11,740. The majority of these admissions were for surgery.

The definition of obesity

‘A chronic disease characterised

by excessively high body fat in relation to lean body

tissue.’

The scale of the problem

Obesity is defined by a body

mass index (BMI) of greater

than greater than 30kg/m2

Obesity is continuing to increase each year in both men and women.

If the increasing obesity population trend continues, it is predicted that the prevalence of obesity in the year of 2010 will be about 19% of men and 25% of women.

Obesity in Scotland

14% of men and 17% of women

are classified as obese (BMI >30).

Even more worryingly, about

20% of Scottish children

are overweight.

Health risks of obesity

There is an increased risk of:

Coronary heart disease Stroke Gall stones Type 2 (non-insulin dependant) diabetes Some cancers (colon;breast;possibly uterine

and ovarian) Bone and joint disorders (excess pressure on

knee, ankle and hip joints) Respiratory problems (excess weight over

lungs)

Causes of obesity

The causes of obesity are complex and are often interrelated.

However, the two most likely causes of the steep rise in the prevalence of obesity in the last twenty years are:

the decrease in physical activity both at work and at leisure

the energy-dense (high fat) diet currently consumed.

Although the average total energy intake has actually decreased over this time period, the energy output has decreased to a greater extent, resulting in a positive energy balance, which ultimately results in obesity.

Treatment of Obesity

Obesity is treated by reducing energy intake, increasing energy expenditure or a combination of both.

Current evidence would suggest that weight loss is more likely to be maintained if levels of physical activity are increased by permanent lifestyle changes in addition to reducing the amount of fat in the diet.

Treatment of Obesity Pyramid

A small percentage of those who are obese go on to

have surgery such as Gastric Bypass

surgery

Most of those who are obese make changes

in there lifestyle to help reduce their weight.

If the person struggles to lose weight

through lifestyle

changes they may choose to

try certain medication.

Individuals who maintain a physically active lifestyle tend to maintain a desirable level of body composition (12-15% fat in males, 20-30% in females).

Effect of exercise on body composition and weight

control

For individual who are trying to lose weight by only reducing their food intake, the addition of exercise has many benefits:• increased energy deficit• increased relative loss of fat while preserving

‘active’ lean tissue• prevents fall in BMR which often accompanies

low-energy intakes• provides significant benefits to overall health

(Physical activity does not need to be strenuous to achieve these benefits)

A negative energy balance of 29.4 MJ (7000kcal) is required to lose 1kg of body fat, regardless of whether this deficit occurs slowly or rapidly.

For example, a deficit of 420 kJ/day between energy intake and energy expenditure will result in the loss of 1kg after 10 weeks (420x7x10=29,400kJ),

Problem 1 – How long would it take to lose the same weight with an energy deficit of 2100kJ/day?

Answer - same fat loss after only 14 days (2,100x14=29,400kJ).

Example

Let us assume that an individual wants to lose 10kg of body fat - this represents a total energy deficit of approximately 294MJ.

Problem 2If the desired energy deficit is 2MJ/day

(which can be achieved by increasing energy output by 1 MJ/day and reducing energy intake by 1MJ/day), how long would it take to lose 10kg

It would take approximately 147 days (21 weeks) to lose 10kg of fat.

PROBLEM 3 - The same fat loss could be achieved by creating an energy deficit of only 1MJ/day. How long would this take?

PROBLEM 4 Conversely, if the energy deficit was increased to 4MJ/day how long would it take to lose the same 10kg of body fat

It would take approximately 147 days (21 weeks) to lose 10kg of fat.

Answer - 10 weeks (294/4=74 days = approx. 10 weeks).

Many nutritionists recommend a fat loss of no more than 0.5-1.0kg per week, which is achieved by an

energy deficit of approximately 2-4MJ/day.

Aerobic forms of exercise of moderate intensity and reasonably long duration - e.g. Brisk walking, jogging, swimming, cycling, golf, dancing - seem to be the most effective for fat loss in addition to conferring many other health benefits.

Many health authorities, including the Health Education Board for Scotland (HEBS), now recommend the accumulation of atl east thirty minutes of moderate-intensity physical activity over most days of the week.