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Exercise Recap + Metabolism Info

This month I want to explore two factors about your body systems. Exercise, and metabolism. We’ve discussed reasons why you should be exercising quite a lot over the last year or more. But here’s some key points for you to remember:

1. Your body was not designed to be stationary, it was designed to move all the time. In previous times daily tasks required a lot of manual and physical labour to achieve, but now we have machines that make those daily tasks simpler and without intense or prolonged physical exertion. You are working harder with your mind now and as such are likely mentally exhausted but not physically (think internet and computers and how much you are doing without moving apart from arm movements to operate the keyboard and the mouse).

2. The body has incredibly efficient systems for allowing continuous extended movement as long as the intensity is low-moderate (think walking, light moves), this is due in part to the aerobic energy pathway which can produce as much as 32 molecules of ATP (which is the energy currency of your cells) from just one molecule of glucose or 129 ATP from 1 molecule of palmitic acid (from lipid metabolism) as long as oxygen is involved.

3. Movement and load will stimulate your bones and muscles to grow stronger, and condition your heart and lungs to improved circulation throughout the body.

Action Steps: You can make it super simple, go for a walk, ride your bike, go for a swim, take your kids to the park and run after them, push them on swings, hang off trees, and generally just move and play. Or you can make it more involved and specific, and learn something new. Perhaps you could try tai-chi at the foreshore, outdoor beach yoga at rainbow beach, bootcamp in the park on a Friday or Saturday morning, boxing on a Wednesday night, a Pilates class on a Tuesday morning, stand up paddle boarding or kayaking at high tide, learn to surf at double island point or a personal training session or assessment to discover what it is your body needs.


Just about every disease lists exercise as a preventative measure or to help manage symptoms.

Here’s your aim, try to get into the habit of doing some physical activity every day for at least 30 minutes. If you’re feeling very unfit start easier but you must work up to the 30 minute mark for your minimum health benefits to work. Then try to get some progression happening. This means once you nail the thirty minutes each day and it becomes something you ‘just do’ push for more. Either more time, more intensity or add in a different type of exercise. Something like resistance training will get you good gains in muscular strength, stimulate your bones to grow stronger and make the other activities you do much easier due to better muscle strength.

Let’s look at metabolism now:

If you look at the food you’re eating as well as the exercise you're doing this should help the overall effect of your fitness efforts. It would be a good starting point to keep a food diary for a week or even 3-4 days just to see what you are actually eating.

When you look at metabolism in the body, what isn’t used immediately or stored in the muscles and liver as glycogen for later use; gets converted to triglycerides and stored in adipose tissue. Adipose tissue has an almost unlimited storage capacity. So what that means is: any excess foods get converted to fats (triglycerides) and stored in fatty tissue of which you’re body has practically unlimited capacity for (obesity).

Carbohydrates end up as triglycerides, fats end up as triglycerides, proteins are used to produce ATP, make new proteins for growth and repair, excess is converted to triglycerides, ketone bodies or glucose (which is used for energy). So it doesn’t really matter if you reduce your intake of fats and up your carbs, they still convert to triglycerides. What matters is only eat what you need for metabolism (the sum of all chemical reactions involved in maintaining the dynamic state of a cell or organism and is vital for growth and reproduction, for the continuation of life) and to support the energy you use in daily activities. If you’re noticing a ‘creep’ of weight, chances are you are consuming too much food for your day to day needs.

When you’re figuring out how much you need it might be a good time to work with a nutritionist or dietician to help figure it out.

Obviously this is a very simple explanation of a complex process that your body goes through continuously. The other interesting thing about metabolism processes is what happens from 0-4 hours within eating and then after 4 hours.

Let’s look at these different functions:

From 0 -4 hours post eating you are in an absorptive state, nutrients are absorbed and begin to enter the blood. The main major metabolic reactions are the oxidation of glucose for ATP, and the storage of excess fuel and nutrient molecules in hepatocytes (liver cells), adipocytes (fat cells) and skeletal muscle fibres. There are many reactions taking place when glucose and other nutrients are readily available, most are storage functions for later use of when food is unavailable. Insulin is also activated and promotes further synthesis and storage functions including entry of glucose and amino acid into cells.

Four hours after eating you are in the post-absorptive state, where glucose and other nutrient absorption has slowed or stopped. Blood glucose starts to fall. However plasma glucose level must be maintained within a narrow range for homeostasis. During this time predominate reactions are the breakdown of glycogen from the liver – approx. 4 hr supply, lipolysis where glycerol is used in gluconeogenesis where fatty acids under beta-oxidation. Gluconeogenesis from lactic acid and amino acids. Oxidation of fatty acids, lactic acid, amino acids and ketone bodies. And breakdown of muscle glycogen. All of these reactions produce ATP from stored nutrients to allow your body to continue to function and maintain homeostasis.

Here’s something I’d like you to think on further. If you’re eating and snacking regularly when are you going to access your stored nutrients/fats? If you have breakfast at 6am, snack at 9am & 11am, Lunch at 1pm, Snack at 3pm and dinner at 6pm, dessert or cup of tea at 8pm, when does your body have time to go into a post-absorptive state and use the stored energy? It will continually be in an absorptive state all day, and only at night will it work into the other system where stores are used.

There are also neurological systems which affect digestion and body function; the Sympathetic response of the Autonomic Nervous System works in times of physical or emotional stress and is called the ‘fight or flight’ response. During this time nervous activity is geared towards supporting body functions that can support vigorous physical activity and rapid production of ATP. It also reduces body functions that favour the storage of energy. During the parasympathetic response ‘rest and digest’ activities are favoured or enhanced. The nervous system supports body functions that conserve and restore body energy. This allows food to be digested and absorbed.

So again have a think about your eating patterns and your exercise and busiest parts of the day. Should you expect your body to be good at digesting while you are getting ready for work and school and moving and exercising and being busy at the start of the day? Or would it make more sense to allow your body time for digestion in a time frame of the day when things are a little calmer? I’m not going to tell you when and how you should be eating as different conditions such as diabetes will affect your eating patterns, so there is no plan here. Just some information and questions for you to consider in your quest to lose, maintain or gain weight as you need to when you consider your requirements for energy, your lifestyle, when the busiest times of the day are for you and if you can shift into the post-absorptive state to use up some of that stored energy.


Sarah Booth


AIAS Study Smart Anatomy, Physiology & Pathology 1. (2015, November 30). Lesson 20: Nutrtion & Metabolism. Brisbane, Queensland, Australa.

Derrikson, G. J. (2014). Principles of Anatomy & Physiology. United States of America: Wiley.

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