Exercise in any form, be it walking, running, dancing, cycling or resistance training has a major part to play in our health and well-being. Exercising for even 30 minutes a day can provide significant benefits to your physical and mental health.
Exercise and the gym is seen as a way of helping people stay in shape and lose weight but just how effective is the gym for weight loss?
I imagine the majority of people who go to the gym do so to feel good, be healthier but more importantly look good too.
Many people will invest in a gym membership with the belief that it is the key to their success.
So why do so many people who go week in week out look exactly the same years later?
Because people focus too much on exercise and not enough on their nutrition and lifestyle!!!
Quite frankly, people think the gym will do more for them than it actually does.
They assume because they go to the gym that it will equal out their lifestyle.
I even see people go to the gym, maybe take part in a group class or exercise session and then sit in the cafe with a milky coffee and toasted buttered tea cake or muffin afterwards...and then wonder why they aren't losing weight.
As painful and hard as exercise can be at the time, it is much easier for many to commit to a few hours of exercise a week, instead of changing their diet or managing their lifestyle.
But focusing on exercise and the gym for weight loss may be a waste of your time.
The purpose of exercise in weight loss is to help create a Calorie deficit, by increasing the amount of energy we use.
The issue is exercise only makes up approximately 5% of your daily energy usage.
This means when people put all their effort and attention in to exercising, they are focusing on a small piece of the puzzle.
How exercise impacts energy expenditure is also mixed with huge individual variability.
Some studies show that when people exercise it increases their overall energy expenditure, which you would expect right?
But other studies show exercising actually decreases overall energy expenditure as people then compensate by reducing their typical daily activity levels (Hall et al., 2012).
This means that for some going to the gym may even result in less energy expended.
How does exercise impact appetite?
Not only can exercise have a wide variability on people’s overall energy expenditure but it can also affect appetite and energy intake.
Exercise may reduce hunger and appetite post-exercise by altering appetite regulating hormones.
You may have experienced it yourself, after a good training session when you really don’t want to eat.
Exercise tends to reduce acylated ghrelin (a hormone that increases appetite) and increases PYY and GLP-1, two hormones which make us feel more full (Schubert et al., 2013).
However, for others, exercise leads to increased appetite and eating more.
Although evidence suggests exercise doesn’t lead to an increase in appetite and energy intake with 65% of studies showing no change, only 16% actually decreased energy intake, whilst 19% increased energy intake (Blundell and King, 1999).
Interestingly, the studies show appetite is more likely to decrease in overweight or obese individuals whilst those classed as leaner participants are more likely to see an increase in appetite.
The type of exercise may also play a role in its impact on our appetite and energy intake.
Aerobic exercise has been shown to reduce neuronal responses in the brain which reduces food pleasure and reduced motivation to eat (Evero et al., 2012).
This suggests aerobic exercise may help reduce the motivation to eat, especially pleasurable foods which tend to be higher in Calories.
Individuals who do moderate to low levels of exercise are more likely to experience exercise-suppressed energy intake whilst those who have high levels of activity are more likely to see the opposite (Schubert et al., 2013).
However, this doesn’t mean those that exercise more and use more energy then manage to eat all those Calories back.
Using physical activity to lose body fat is more effective in men than women (Hagobian and Braun, 2010).
In fact, exercise without an accompanying reduction in Calories is not very effective for weight loss in women at all (Jakicic et al., 2006).
Studies that recorded 16 months of supervised aerobic exercise found men who ate ad libitum (what they want, when they want) lost body fat whilst there was no change in women who did the same.
This suggests that after aerobic exercise, women are more likely to re-compensate the energy they use by eating more, therefore not losing body fat.
Sex-based hormones may alter appetite, energy intake and energy expenditure that stimulate appetite and energy intake whilst potentially suppressing energy expenditure in women.
Hagobian and Braun (2010) found women had increased ghrelin and reduced insulin which would likely increase appetite whilst a further study found similar results with decreased leptin and insulin levels after 12 weeks of exercise in women.
So, what does all this mean?
Exercise uses energy up which can help create a Calorie deficit needed for weight loss.
However, the amount that exercise creates a deficit varies from person to person.
Studies suggest people react differently to exercise with some eating less, some eating more but the majority with no change
Studies suggest that it is unlikely that exercise increases people’s appetite to the point that they gain weight, back to maintenance perhaps in some cases.
But that exercise can reduce overall movement and energy expenditure, reducing the deficit and potentially pushing the person in to a Calorie surplus.
This is more likely to impact women due to exercise induced changes to hormones.
In simple terms this means unless you consciously take action to reduce your energy intake through nutrition and make a conscious effort to move more throughout the day, going to the gym or exercising will not do much for your weight loss goals, especially if you’re a woman.
To conclude, you can not rely solely on exercise to help you achieve your weight loss goals.
You must alter your food intake!
You must consciously move more!
You must take control of your lifestyle!
References
Blundell, J. and King, N. (1999) 'Physical Activity and Regulation of Food Intake: Current Evidence.' Medicine and science in sports and exercise, 31(11 Suppl), 1999 Nov,
Evero, N., Hackett, L., Clark, R., Phelan, S. and Hagobian, T. (2012) 'Aerobic Exercise Reduces Neuronal Responses in Food Reward Brain Regions.' Journal of applied physiology (Bethesda, Md. : 1985), 112(9), 2012 May,
Hagobian, T. and Braun, B. (2010) 'Physical Activity and Hormonal Regulation of Appetite: Sex Differences and Weight Control.' Exercise and sport sciences reviews, 38(1), 2010 Jan,
Hall, K. D., National Institute of Diabetes and Digestive and Kidney Diseases, N., Bethesda, MD, Heymsfield, S. B., Pennington Biomedical Research Center, B. R., LA, Kemnitz, J. W., Institute for Clinical and Translational Research, U. o. W., Madison, WI, Klein, S., Washington University School of Medicine, S. L., MO, et al. (2012) 'Energy balance and its components: implications for body weight regulation.' The American Journal of Clinical Nutrition, 95(4) pp. 989-994.
Jakicic, J. M., Department of Health and Physical Activity, P. A. a. W. M. R. C., University of Pittsburgh, Pittsburgh, Pennsylvania, USA., Otto, A. D. and Department of Health and Physical Activity, P. A. a. W. M. R. C., University of Pittsburgh, Pittsburgh, Pennsylvania, USA. (2006) 'Treatment and Prevention of Obesity: What is the Role of Exercise?' Nutrition Reviews, 64(suppl_1)
Schubert, M., Desbrow, B., Sabapathy, S. and Leveritt, M. (2013) 'Acute Exercise and Subsequent Energy Intake. A Meta-Analysis.' Appetite, 63, 2013 Apr,