The world of weight loss is complicated enough as it is. With many different opposing views as to what works and what doesn’t, it can be hard to know who to trust and what to do for the best.
It doesn’t help that the terminology around weight loss is unnecessarily technical, with endless references to BMI, BMR and Macros, it can seem like another language.
But worry not, we are here to demystify weight loss jargon for you. Read on to learn more.
What is BMI and what does it mean for my health?
BMI stands for body mass index. It is a way of measuring your ‘body mass’ based on your weight and your height. It is often used to categorise people into different weight categories such as underweight, ideal, overweight or obese.
However, despite being a common method of establishing your health risks, it has a number of key flaws. For example, it doesn’t distinguish between body mass which is comprised of dense muscle and body mass which is comprised of pure fat. This means that if you are a muscular rugby player or weightlifter, you may be classed as obese, when in reality you are mostly comprised of muscle, and not fat. Still, nonetheless it’s a term you should be aware of, as, despite its limitations it can give you an indication of where you are currently- with the ideal BMI being in the region of 18,5-24,9.
What about BMR?
This term refers to your basal metabolic rate- or the rate at which you expend energy when at rest. Whilst we normally think about energy expenditure as something which occurs during exercise or movement- we actually expend around 70% of our energy just via performing basic bodily functions such as keeping our heart beating and digesting our food.
People often use their ‘bad metabolism’ as an excuse for failing to lose weight, but there is actually some truth in this. Even if we are the same size and build as somebody else, we can have a vastly different BMR, which means if we eat the same number of calories and do the same amount of movement, we will still end up with a different weight outcome.
Factors which influence our BMR include:
- Genetics
- The amount of omega 6/ omega 3 we have
- Our gut microbiome
- Our stress levels
So again, its definitely worth thinking about out BMR when it comes to weight loss, but luckily, it is not set in stone. Even if we currently have a low BMR which leads us to not expend much energy when at rest, we can take steps to alter this. Exercising, eating more omega 3 rich foods, improving our gut health and lowering stress can influence our personal BMR, making it easier for us to maintain our weight.
Ok so what is BIA then?
BIA stands for Bioelectrical Impedance Analysis. It is yet another way of measuring your body mass. Although, this method is actually much more accurate, personalised and helpful than the generic BMI measurement.
This is because this measuring method is able to distinguish between the areas of your body which are comprised of fat, muscle and other lean tissue.
This gives you a good indication of the percentage of your body mass which is made up of fat, making it easier to set specific weight loss goals.
BIA involves the use of a special machine which uses small electrical signals through the body to identify and measure different types of body mass. It is completely painless, and many personal trainers, nutritionists and weight loss coaches have access to them, so if you are interested, it shouldn’t be too difficult for you to get your numbers.
What are macros and why do they matter for weight loss?
You may have heard of people talking about meeting their macros, macro counting and so on, and wondered what on earth they were talking about. But its actually pretty simple. Macros are simply an abbreviation for macronutrients, which make up most of our diet.
Macronutrients are comprised of:
- Protein
- Fats
- Carbs
And for people looking to lose weight or maintain a certain body mass, they may aim to manipulate the ratio of these three ‘macros’ to try and meet their health goals. Of course, other dietary interventions also aim to influence the number of macros we consume- for example by urging us to go low fat, low carb or high protein.
There is evidence that a low carb diet can help facilitate weight loss quicker than a low-fat diet, and that it can also reverse prediabetes and improve metabolic health. But it is always important to take a bigger overview when making big dietary alterations.
For example, by going low carb we can inadvertently cut back on the quantity of fibre we need to feed our ‘good gut bugs’, and this can have an adverse effect on our weight, as our microbiome (the trillions of bugs living in our large intestines) can impact our metabolism, and our risk of weight gain.
Similarly, by going low fat, whilst we may reduce our calorie consumption, we may also fall short of essential fatty acids, as well as missing out on the fats we need to maintain a healthy hormone balance.
This doesn’t mean we should never alter the ratio of our macros to support our main health aspirations, but its just to be aware that in the longer term, we want to ensure we get enough of the nutrient dense items our bodies need to thrive.
What about micronutrients? Can they influence my weight?
Micronutrients do not have a direct impact on your weight. They are contained within proteins, fats, and carbs, but they are especially dense in wholefoods such as vegetables, fruits, seeds and spices. They are an essential part of our diet, and when we alter our macros to say avoid carbs, or fats, we need to ensure we do not lose out on these along the way.
Key takeaways:
- Weight loss terminology can be confusing, but you only need to know a few key terms
- Your BMI is an estimate of your body mass, but doesn’t distinguish between fat and muscle, making it unreliable
- BMR is your basal metabolic rate- the rate at which your body expends energy when at rest- it is different for everyone but can be improved through lifestyle
- BIA is a better form of measuring your body mass- using electrical currents to measure your fat and muscle stores
- Macros include carbs, proteins and fats, and should be include adequate micronutrients for a healthy diet.
The bibliography:
1 Kahn HS, Bullard KMK. Beyond Body Mass Index: Advantages of Abdominal Measurements for Recognizing Cardiometabolic Disorders. In: American Journal of Medicine. ; 2016. doi:10.1016/j.amjmed.2015.08.010
2 Küçükkubaş N, Aytar SH, Açlkada C, Hazlr T. Bioelectric impedance analyses for young male athletes: A validation study. Isokinet Exerc Sci. 2020. doi:10.3233/IES-185209
3 Yetgin MK, Agopyan A, Kucukler FK, et al. The influence of physical training modalities on basal metabolic rate and leptin on obese adolescent boys. J Pak Med Assoc. 2018.
4 Logan SL, Spriet LL. Omega-3 fatty acid supplementation for 12 weeks increases resting and exercise metabolic rate in healthy community- dwelling older females. PLoS One. 2015. doi:10.1371/journal.pone.0144828
