The basics of weight loss
In the fitness industry you hear claim after claim of people who say they've lost miraculous amounts of weight will little effort and little change. Usually all they say they did was just workout x or eat supplement x. Don't believe them. Over 99% of the time these people will either be:
a) Trying to sell you their "Magic" workout/supplement/diet or
b) Simply misattributing the cause of their weight loss to the product or exercise rather than far simpler reasons like they've started paying attention to their diet and are eating fewer calories
Calories and the key to losing weight
Weight loss doesn't have a magic bullet, while there are plenty of other factors that may hinder your ability to lose fat, at the end of the day it all comes down to calories in vs calories out. You continually eat more than you burn in a day, known as a caloric surplus, the calories that don't go to building muscle will be stored as fat. You eat less than you are burning in a day, known as a caloric deficit, you will force your body to start burning your adipose tissue, or fat. Despite the constant back and forth of people claiming it doesn't matter, it comes down to one of the most fundamental laws of thermodynamics. If it really didn't matter about the calories in vs calories out, then congratulations, you just found a way to produce unlimited energy and are now sitting on a trillion-dollar finding! As appealing as it is, we can’t change reality. It’s true there are numerous individual differences that can make one person lose weight faster or slower (exercise, body composition, genetics), but that different at the end of the day isn’t as significant a factor as how many calories you’re eating in a day.
Why then can some people seem to eat whatever they want and never gain weight and others balloon out like crazy? While it’d take a whole other article to go into detail, as there are many legitimate factors than can affect the rate at which you lose fat, if you average out peoples body composition, height and weight, we all pretty lose or gain fat at the same rate; it all comes down to calories in vs calories out.
Dropping the weight
Okay so how you can use this information yourself? First you need to use a Basal Metabolic Rate (BMR) calculator, which works out how many calories you burn in a day, just by existing. This is your baseline calories so if you eat less calories in a day that your BMR, you will lose weight, and if you eat more, you will gain weight. Exercise will add onto the number of calories you burn in a day, as will daily activities like walking or doing your job.
Knowing the amount of calories, you had in a day is why counting calories is so effective for weight loss, while the accuracy of foods labels is never 100%, just trying to stay under that BMR is the simplest, and most sustainable way to lose weight.
So what happens when you start dropping the kilos? When you first go into a consistent caloric deficit, expect to see a rapid drop in your weight, this won’t be solely fat lose though, but rather your muscle glycogen stores are being depleted and you're losing a lot of water weight. If you’re still eating a nutritious diet this isn’t a bad thing!
How can I safely lose weight?
So, what's a safe caloric deficit and how much is too much? While it’s understandable and tempting to believe you can drop 15+ kg in a month, the reality is a bit more conservative than that. The good news is that while older evidence was supporting around ~450g of fat loss per week as a safe maximum, evidence is growing to support a weight loss of about 450g-900g per week. Going back to our calorie counting, it takes a weekly deficit of ~3500 calories to lose half a kilo a week, or ~500 calories below your maintenance calories a day.
To lose 1kg of fat a week, you need to double that, or a 1000 calorie deficit a day. To lose 2kg a week it’s double that, a 2000 calorie deficit. For 90% of the population losing 1kg a week is difficult to do, losing more than that is not only unsustainable but will likely lead to macro or micronutrient deficiencies unless have seen a registered dietician.
Practical recommendations
- Cutting your calories this severely is problematic because it affects all sorts of hormones especially those which affect satiety and hunger; so not only will you have less energy to go around with, you’ll crave food more and more. Basically it’s the perfect recipe for breaking your diet.
- Something to note while you’re attempting to lose weight; as you start shedding the kilos, the number of calories your BMR will also drop (fat requires energy to stick around after all) so over time you’ll need to increase your deficit.
- If you are counting calories and trying to lose weight, try a moderate deficit of ~250 calories below your BMR for a week minimum before increasing it. It’s better to start slow and be consistent than go big and crash early.
Take home points
The key to long term diet success if moderation, if you can't imagine yourself eating your planned diet in 5 years’ time, you’re doing it wrong, it needs to be sustainable. A calorie deficit of around 20% of your maintenance calories is a good place to start. Unfortunately, there aren’t any quick fixed, just incremental lifestyle changes that eventually lead you to your goal.