Exercise and weight loss – the basics
Author: Matt Whitaker, Digital Health Lead/20 March 2018
We have had a range of blogs covering many different aspects of nutrition. But we have not covered exercise in any great detail. This blog introduces the basics about different types of exercise. Also, why they may be beneficial for overall health and weight loss.
Physical activity or exercise?
Physical activity is defined as any movement produced by skeletal muscles contracting that causes energy to be expended at a greater rate than when one is resting. It could be argued any movement is technically physical activity.
Exercise is a subcategory of physical activity. It is more premeditated and structured. With intentional movements usually aimed at improving overall fitness, health and/or body composition.
This blog will be focusing more on exercise.
Regular participation in exercise has a direct positive impact on health and longevity in all populations.
Overall exercise has a range of benefits. Some that are consistent regardless of the type of exercise performed and some that are more specific to a certain exercise category. Known benefits include:
Improved cardiovascular health
Fat reduction (subcutaneous and visceral)
Stronger bones and joints
Improved functional strength
Increased lung capacity
Enhanced immune functioning
Enhanced strength, flexibility and balance
Improved aerobic endurance and stamina
Better sleep quality
Reduced stress and improved mood
Reduced risk of mental health issues
Improved blood glucose regulation
Increased insulin sensitivity
Greater energy levels
Upgraded pain management
These positive effects may be the reasoning behind why regular exercise tends to lead to a risk reduction of most chronic conditions.
Daily physical activity with minimal sedentary time throughout the remainder of the day
150 minutes of moderate intensity activity each week, made up of bouts of 10 minutes or more.
Alternatively – 75 minutes of vigorous intensity per week.
Resistance activities twice per week.
The recommendations for older adults (>65 years) are similar, with the addition of:
Older adults at risk of falling should incorporate activities to improve their balance and co-ordination twice/week
Overall any increase in exercise is likely to show benefits. However if weight loss is the goal (in overweight and obese individuals) these activity levels should be increased to, and ideally doubled to 300 minutes throughout the week (and should be accompanied by dietary changes).
Types of exercise
For the most part exercise can be broken down into three main categories:
Anaerobic (High intensity interval training)
Aerobic means ‘with oxygen’. So aerobic exercise is when enough oxygen is utilised to meet energy needs. It usually involves the body’s large muscles moving in a rhythmic manner for a sustained period of time. It is the most sustainable type of exercise and is characterised by increased heart rate, breathing rate and sweating. Some examples include: brisk walking, jogging, running, cycling, rowing, swimming, housework, gardening, dancing and gym classes.
The reason many people perform aerobic exercise when seeking weight loss is to aid them in creating an energy deficit. Following the classic ‘eat less, move more’ message. But this does not consider the substantial limitations with this message, previously discussed here.
To add to these limitations – some may religiously track calorie expenditure; whether it be on their phone, watch or using gym equipment. These estimates can be drastically inaccurate and easily misinterpreted. For example, if one finishes a 60 minute jog on a treadmill and the number of calories burned comes out as 600 this individual may consider this to be a significant contributor to creating an energy deficit. However the number on the treadmill does not consider calories what would have been burnt if the individual was say, sat at home. Sitting down for an hour could burn 150 calories. meaning the added benefits of the run has already dropped to 450. And that is without considering the vast overestimations of these machines and the commonly seen non-exercise based compensations.
The calorie expenditure reported also does not consider improvements to fitness, which would increase efficiency of performing the exercise. This means that overtime one will need less energy to perform the same level of exercise. As fitness improves, so any exercise contribution to an energy deficit will reduce.
This does not mean aerobic exercise is useless by any means. It has absolutely been shown to improve most of the health factors listed before. But its role in sustained weight loss may be more questionable.
High intensity interval training (HIIT)
Technically this section should be discussing anaerobic exercise, which is powered by metabolic pathways not regulated by oxygen (anaerobic means ‘without oxygen’). This type of exercise is only sustainable for seconds and is not as regularly performed (apart from resistance exercise which has its own category below). But HIIT is becoming more popular, so I will briefly discuss it here.
Interval training involves alternating periods of higher intensity, unsustainable activity with periods of either rest or lower intensity, steady state activity to act as a recovery interval. One variation for this style of training is HIIT. Exact pathways for the effectiveness of HIIT are yet to be concluded, though some believe they are linked to training time spent near to VO2max (the maximum rate at which the heart, lungs and muscles can effectively use oxygen), a high degree of muscle fibre recruitment and additional stimulation of associated cardiovascular and cellular signalling pathways.
HIIT training protocols vary in time spent in the high intensity state and the recovery intervals dependent on the individual’s preference and fitness state. Some protocols see very high intensity exercise for less than 30 seconds followed by rest/passive recovery until ready to repeat the higher intensity interval. Some see the high intensity intervals drop to less than 10 seconds. Different protocols will utilise different metabolic pathways depending on the time and/or intensity of the bouts and an optimum option is far from universally accepted.
Refilling glycogen (essentially stored glucose) stores is a key mediator in improving insulin sensitivity following exercise, therefore a greater depletion of muscle glycogen seen after HIIT may improve glucose uptake within worked muscles, thus temporarily improving insulin sensitivity. For this reason, HIIT may play a role in managing obesity and the metabolic syndrome by reducing insulin resistance.
In addition to this HIIT may serve as a time-efficient way of reaping exercise benefits for those with busy lifestyles!
The safety of HIIT is an area that is still being explored and is worth considering before undertaking this exercise protocol if one is overweight/obese. This is necessary due to the intensities worked at when undertaking HIIT which may be unsuitable, or even dangerous, for those who do not partake in regular exercise. It is recommended that individuals seek advice from their GP before undertaking a HIIT regime. And, even then, they should build up intensity and frequency of performing their protocol.
Resistance training is when the muscles have to contract to work against a resistance. This can be either in the form of pushing or pulling, where a complete movement has both concentric (shortening of the muscle whilst it is contracting) and eccentric (lengthening of the muscle whilst it is contracting) parts.
Resistance style movements usually last a matter of seconds and are repeated for a number of repetitions. They are often split into numerous sets to maximise muscular stimulation. Some examples are: weight training, working with resistance bands, carrying heavy loads, heavy gardening, push-ups, sit ups and other body weight movements.
Muscle tissue requires more energy to optimally function when compared to fat (gram for gram), meaning if you have more muscle and less fat your basal metabolic rate (the amount of energy your body requires for subconscious functions) will increase. This will help in sustaining weight loss. Resistance training tends to increase muscle strength and size. This means resistance training can help to increase your metabolic rate and thus your energy requirements.
Having stronger muscles will also improve their functionality which will have a positive effect on one’s core strength, flexibility, balance and posture.
As with nutrition, how sustainable an exercise is will be the greatest predictor of its success.
One very important consideration that many bypass is a clear progressive structure to their exercise programme. The human body is incredibly efficient. If it is presented with a similar stimulus on a regular basis it will become more effective at responding to that stimulus. To consider this in exercise – your body will start to use energy more efficiently. Meaning it will take you less energy to perform the exercise if you do not add any element of progression. Energy usage efficiency is one factor measured when examining athletes running economy. The most economic (and successful) runners having the highest energy efficiency i.e. they use less energy.
Setting up progression will vary on the type of exercise. Whether it be adding an additional few minutes to your run on a weekly basis, ramping up working intensity, or adding more weight/counteracting force to a resistance movement overtime. Reviewing progression is fairly simple. Are you running faster, are you cycling at higher intensities, are you moving more weight or for more repetitions? If not then review your current progression structure.
Warming up and cooling down properly are hugely important factors. They would quite easily warrant a blog of their own. The recommendations will vary massively dependent on the type of exercise, the planned duration and the intensity/level one is performing at. At a basic level it is advisable to perform dynamic stretches before exercise. Then followed by ramping up intensity to the intended working rate. Meaning if you are aiming to run at 12km/h you should maybe start at 6km/h and steadily increase. Following exercise, static stretching and/or foam rolling may be useful to avoid delayed onset of muscle soreness (DOMS) and muscle tightness.
Ultimately when examining weight loss, exercise is another piece to the puzzle alongside nutrition, stress, sleep and overall behaviour change. Exercise, if performed in isolation may have limited benefits if ones goal is weight loss, however when it is combined with an appropriate dietary approach one can stick to then it absolutely has potential to accelerate weight loss and aid in sustaining any reduction in weight.
If ones goal is overall improvements to health then it is very safe to say regularly performing exercise will help to achieve this.