I've seen lots of posts on here with regard to losing weight. I've tried a few times to answer those posts but always feel I haven't provided enough information for it to be really useful. So I decided to write a much longer post about the science behind weight loss and here it is!
While Couch25k is not designed as a way to lose weight many people find themselves here as part of a wider goal to lead a healthier life and shed some pounds. Lots of people post here asking why they have not lost weight and in some cases why they have gained during the programme. Hopefully this post will provide you with some of the reasons why this happens.
Firstly, in order to lose weight you must be in a calorific deficit - burning more calories than you consume. Weight loss plans such as Slimming World, WeightWatchers et al are designed to put you in a deficit by swapping high calorie “unhealthy” foods for lower calorie “healthy” choices. If you are on one of these plans and it is working for you stick with it – you are in a calorie deficit! It is however perfectly possible to overeat “healthy” foods so if your weightloss has stalled read on and hopefully you will find some answers as to why.
Lets address the basics.
What is a calorie?
A calorie (kcal) is a unit used to measure energy. More precisely it is the energy needed to raise the temperature of 1 kilogram of water through 1 °C, it's commonly used to measure the energy value of foods.
3500kcal roughly equates to 1lb of fat.
What is a calorie deficit?
A calorie deficit is burning more calories than you consume.
What is a calorie surplus?
A calorie surplus is consuming more than you burn.
What is BMR?
BMR is Basal Metabolic Rate. It is the number of calories needed to keep you alive. No activity is included in this – think coma!
What is NEAT?
NEAT is Non-Exercise Activity Thermogenesis. It is the energy expended for everything we do that is not sleeping, eating or sports-like exercise eg walking to work and at work, housework etc
What is TDEE?
TDEE is Total Daily Energy Expenditure. This is BMR+NEAT+calories burnt from exercise.
Eating the same number of calories as your TDEE will mean you maintain your current weight, less will mean you lose, more that you gain. Other things can affect scale weight but more on that later.
How to calculate your TDEE.
There are many calculators available online which use various equations to help you to work out your TDEE. The number of calories needed will vary from person to person – how tall you are, how much you weigh and how active you are all affect this number. If your weightloss has stalled you don't need an online calculator as you can work out your own TDEE by logging what you eat over the course of a week (using a site such as MyFitness Pal) adding it all up and dividing it by 7. It is important to note at this point that you do need to log as accurately as possible by weighing and measuring the food you eat. I know this puts a lot of people off but if you are determined to lose it really isn't as bad as it sounds!
Once you have established your TDEE you then need to start eating less in order to lose. I said earlier 3500kcal =1lb so cutting your intake by 500 calories a day will mean losing 1lb a week. For the majority of people this is the number to use. Note that women should not eat less than 1200kcal and men 1500kcal unless under medical supervision. While it may be tempting to accelerate the process by cutting more agressively, like Couch25k, weightloss is best approached with a slow and steady mentality.
Many people use the NEAT+exercise method and calculate their exercise burns separately via an activity monitor. These monitors often overinflate calorie burns (as do machines at the gym) so while it would be nice to think we are burning lots of calories during our runs the reality is that it is probably quite a bit lower than the technology may lead us to believe. If you're eating back exercise calories and not losing this might be something to consider.
Things which can affect scale weight
When we lose “weight” what we actually want to do is lose fat. The weight we see on the scales can vary from day to day depending on a number of factors eg when we last went to the toilet, what types of foods we have consumed. These daily fluctuation are perfectly normal but in terms of what we are discussing here they are not real weight. They are however frustrating as they can mask fat loss. Here is a bit more on one of the most common reasons for the fluctuations:
For those who have a menstrual cycle it is important to remember that this can cause fluctuations in scale weight - some people report as much as 7lbs!
What you eat has an impact too. Salt and carbs both cause the body to retain water but in different ways. I'm not going to go into too much detail about exactly how here but in simplified terms too much salt in the diet is bad for you whereas carbs provide the muscles with glycogen which is a positive thing.
Exercise also causes water retention. When we begin Couch25k we will be using our muscles in a new way. In very simplistic terms this means as we use them we cause tiny tears in them which fill with water. It's nothing to worry about, perfectly normal and will lead to your muscles becoming stronger over time.
Next I'd like to address one of the most common misassumptions about why your weightloss has stalled:
Muscle Weighs more than Fat
It is indeed true that muscle is more dense than fat. As you build muscle your scale weight can remain the same or even increase while your clothes size decreases. This is unlikely to be the cause of your stall in weightloss though. Here's why:
In order to build amounts of muscle significant enough to affect your scale weight you must be in a calorie surplus combined with progressive overload in strength training (what body builders term "bulking"). Females have to work especially hard as they don't have enough testosterone to help grow that muscle. Running is primarily cardio and most people would decrease the amount they do when bulking not increase it.
This does not mean that you're not getting stronger from running or that your shape won't change - it just means that this isn't the cause of the lack of scale movement.
Do remember that weightloss is not linear – meaning that even if you stick rigidly to your 500kcal deficit you won't necessarily see the scale move by exactly 1lb a week. Stick with it though because in the long term you will lose.
If you're still not losing weight after you have acted on all the information contained here please do consult a doctor. There are some medications and medical conditions which do make weightloss more difficult and require medical supervision.
You've made a huge leap forward to a healthier life by commiting to Couch25k and I wish you every success in achieving your weight loss goals.