Obesity and Metabolism: Increasing Efficiency

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When 1 in 4 British adults is obese, it does indeed seem that the UK has become the ‘fat man of Europe’. According to the NHS, obesity levels have more than trebled in the last 30 years and, if things continue, more than half the population could be obese by 2050.

Faced with such a bleak forecast, we have never needed fitness professionals more. It seems that effective combat of this gross phenomenon is going to require the use of every tool in their toolbox. As a personal trainer, you will have no doubt worked with a vast array of eager individuals ready and raring to ‘lose weight’, ‘gain muscle’ or ‘tone up’. But when the problems posed by obesity, such as early mortality, are far more serious than aesthetics, PTs will need to look beyond prescribing targeted toning programmes, towards more comprehensive weight-loss strategies focused on the fundamental importance of a functioning metabolism.

For those who need to lose significant weight, PTs should first turn their attention to manipulating all aspects of their client’s metabolism as an effective and durable way to help keep the pounds at bay. Before entertaining HIIT treadmill sprints and Bikram yoga classes, PTs will know that people with a BMI of >35 (Class II Obese or above) are likely to struggle with even simple exercises. The priority, therefore, is to get them moving in a sustainable way that will ultimately lead to a healthier lifestyle.

Metabolic Components

Daily metabolism – how your body spends energy each day – is dictated by two primary factors. The first is the basal metabolic rate (BMR), the second is voluntary metabolism. While BMR is based on some factors outside of our control, such as age, gender and genetics – explaining why it varies person to person – voluntary metabolism is not. It can be manipulated and amplified easily through voluntary activities (walking, running, hoovering – anything involving movement) which, in turn, will increase calorie expenditure. What’s more, if obese individuals keep moving day after day, they can increase their BMR too.

The third factor influencing daily metabolism and “energy out” is the thermic effect of food (TEF). This describes how the body’s metabolism speeds up in response to having eaten a meal, also known as diet-induced thermogenesis. Though TEF only constitutes 5-10% of energy expenditure (whereas physical activity takes up a chunkier 25-50%), small changes can result in big differences and PTs would do well to encourage any especially overweight clients to increase their TEF through sensible diet choices: lean protein is king with a thermic effect of 30%; strong evidence suggests both very spicy foods and green tea have thermogenic properties; complex carbs, a regular eating habit and drinking lots of water also all help increase the rate at which calories are burned.

obesity metabolism protein

Increasing Metabolism to Combat Obesity

Alongside the importance of diet, PTs can remain astute to the fact that physical activity is the most effective way to boost your metabolism. The broad picture is that a greater volume of activity will in any case will increase the potential for weight loss, as well as promoting EPOC – excess post-exercise oxygen consumption – which sees your metabolism working for hours after a workout.

For fitter clients, aerobic exercise is likely to be the focus as the most efficient way to increase “energy out”. But for those struggling with obesity, the emphasis should instead be on changing daily habits into healthy learned behaviours. Using a 24-Hour Physical Activity Recall, which tracks all significant movement, not strictly ‘exercise’, PTs can assess their client’s day to day routine – are they choosing lifts over stairs; using transport to get to places within walking distance; watching TV instead of getting out and about; online shopping from the sofa instead of walking round the shops?


Every decision matters

In isolation, perhaps these decisions seem unimportant, yet the fact remains that 1 in 4 adults are obese as a result of largely inactive lifestyles. If PTs can help their clients to understand that with every choice to undertake some level of activity – whether it is hoovering the stairs or taking the dog for a longer walk – the more oxygen they’ll be using and the more calories they’ll be burning.

Indeed, a review of obesity studies by Université Laval in Quebec, Canada, concluded that lower intensity exercises done frequently (>5 times a week) is the best solution for the obese client. ‘Lower intensity’ coupled with ‘frequently’ is crucial here, for it is crucial that PTs work with obese clients towards the long-term goal of enjoying exercise. Unlike quick fixes and fads, a long but sustained journey away from low tolerance for, and dislike of, physical activity will in time reap the ultimate benefits: for PTs, satisfaction is rooted in the progress clients make in terms of dietary intake and energy output; for individuals, it is the happiness of a healthier life; as a nation, it is key if we are to begin effectively reducing obesity rates in the UK.