Metabolism myths – the facts about metabolism and losing weight:

Metabolism Myths – the facts about metabolism and losing weight:

Losing weight! This is the main goal for a lot of people when starting a new exercise program. However, very few people will achieve it. Often, they will start like a bull out of the gate. They will do 5 or 6 or 7 exercise sessions a week to get there faster. This is unsustainable and it rarely lasts more than 2 weeks. Often, either injuries occur, particularly overuse injuries or they just quit because it’s too hard to maintain.

Social media trends and advertising influence how we perceive our health. They can often show you that you have to “work hard” and “feel the burn” to get results. This is just not how your body works and is often a one way ticket to failure. In a great article in New Scientist, Herman Pontzer explored myths about your metabolism. We will discuss these as well as what will actually work for you.

Myth 1: Exercise burns kilojoules and boosts your metabolism

– The biggest thing to realise is that when it comes to exercise, more is not better.  Besides initially (in the first few months of starting an intense new program), your total energy expenditure does not significantly go up in the long term.  The hunter-gatherers of Northern Tanzania walk about 19,000 steps a day. Specifically, 19,000 steps for hunters and 12,000 steps for gatherers. They do not have a higher energy expenditure than you and me. Even though they use more energy finding and gathering food, they rest more throughout the day. So, the total per day is not that different to western society.  In addition, you also need to consider that running for 30 min, only uses about 1340kj (78kg male). This is equal to1.25 Mars bars. So, if you ran for 30 min everyday, you only burn the equivalent of 8.75 Mars bars per week. This is not a huge amount.

Myth 2: Exercise alone will make you lose weight

– Unfortunately for this one, the consistent research data is against you.  In a large review of 61 exercise studies, although there “may” be some weight loss initially, this often fades over time.  There was a long term (16 month) study of men and women participating in an exercise program. They burnt an extra 8,360 kilojoules per week (equivalent to running about 30 everyday). Men would lose up to 5 kilograms then plateau and most women lost no weight at all.  The main reason is that as you exercise more, you eat more. So, your body subconsciously matches your energy expenditure with your energy intake, the result being no net loss in the long term.

Myth 3: Kilojoules don’t matter

– Most diets work by reducing the total amount of kilojoules we consume per day.  In general, weighing and counting the amount of kilojoules you eat through food diaries is very difficult. Most people give up before the end of the first day.  When we provided nutrition consultations, we asked our clients to record what they were eating for 1-2 days. This was rarely completed and usually it wasn’t accurate. So, getting a real idea of the amount of kilojoules our clients consumed was very difficult.  This meant working the “energy in, energy out” equation through math’s alone was rarely accurate.  However, whether it is a low-carb, low-fat or intermittent fasting diet you are attempting, all these methods rely on a “kilojoule deficient”. meaning, you are eating less than you burn to lose weight. Consistent research has shown than none of these diets are any better than each other at losing weight.  So what is the answer? Eating low-energy, high-nutrient dense carbohydrates (such as non-starchy vegetables), with most fruits as your main source of energy. Combine this with adequate lean protein (<10% fat) for muscle growth and preservation. Eating high-energy carbohydrates at the right time (after intense exercise) will aid the recovery process. So, eat this when you need it.  Even if weight loss is slow, you body will thank you for it. Sticking to a healthier diet provides you with the nutrients you need for good health, maintenance and repair.

Myth 4: Humans evolved to eat a Paleo diet

– Based on evidence discussed by Herman Pontzer (2021) from studying hunter-gatherer tribes in Tanzania and archaeological evidence. This shows that this ancient community do not have one single diet that was very meat heavy and plant food sparse.  Firstly, diets from all these communities are very diverse and differ greatly. Just like in western society.  Secondly, all these communities eat a combination of plant food and meat. This is dependent on what is available in the local area and cultural norms in the community.  Therefore the “Paleo” diet is a myth. It should be examined for the nutrients it contains, not because it was what our ancestors ate.

Myth 5: Slow metabolism dooms you to be overweight

– People have different metabolisms, a large part we have no control over.  However, having a slow or fast metabolism is a poor predictor of obesity.  In general, people who are overweight have a similar total energy expenditure to those who are in a healthy weight range. What is the difference?  Firstly, if there is a medical reason for a change in your metabolism, such as poor thyroid function, this needs to be addressed. This has long term health consequences, not just for your weight. Seeing your doctor and having regular health checks should discover issues like these and help you get onto them early.  Secondly, extra kilojoules can slowly creep into your diet. This can be from eating a chocolate bar here and another “treat” there.  This doesn’t happen quickly, but slowly over time until it becomes a habit. So, the “extras” that you have are no longer a treat, but become your normal.  Do the opposite, slowly make it a habit to reduce the “extras” in your day. This means a slow reduction in the energy consumption of additional, low-nutrient dense kilojoules.

Myth 6:  If I am not losing weight, I have failed in my exercise program

– Exercising is more than just about losing weight.  The health benefits of exercise are enormous and are beyond just reducing your waistline. Especially when considering the importance of strength based exercises. Exercising and being strong means you can do more and feel better. You are also less likely to be physically limited in what you can do because your body was not strong enough. If can now easily go for a run in the morning, garden all day, ride your bike on the weekends or easily keep up with your kids, would any of these outcomes be considered a failure if you hadn’t lost weight?

In addition, improving your muscle mass through exercise will help in your overall health. Including better management of diabetes, reduced risk of heart disease and better blood pressure management.  Strength based training has been shown to be one of the most consistent ways you can reduce the risk of memory loss and improve long term brain function.

What is the right thing to do for your metabolism?

There are 3 major things to can do help keep your metabolism in the best shape:

Regular strength based exercise

– Building on and preserving your muscle mass is one of the only things in our metabolism we can control.  Increasing your muscle mass through regular strength training (2-3 times a week) helps improve your overall metabolic rate. An added bonus is that you are stronger, have better balance and can manage your blood sugar better.

Make healthy changes to your diet

– Generally, relying on low-energy density, high-nutrient foods such as non-starchy vegetables, most fruits and lean proteins (<10% fat) should be your main sources of energy in your diet.  High energy foods, such as bananas and bread have a place after intense exercise, to help build muscle mass, but in combination with low-energy foods. Treats should be just that, occasional, not a regular in your diet. The more treats you have as part of your “regular” diet, the longer it will take you get your desired outcomes.

If you are worried about your metabolism, see your doctor

– You can tell your hormonal levels, such as thyroid hormone, with regular blood tests.  So, regular testing from your GP will pick up these issues early. Hopefully before they become a problem, so that you can live the healthiest life possible, in the long term.

Pontzer H(2021) Metabolism Myths.  New Scientist, 27^th February 2021, No. 3233.  P32-36.