Ever tried to lose weight and ended up back where you started?
If you cut through all of the noise out there in the diet industry, your weight is determined by the balance between the energy you take on (in the form of food) and the energy your body expends to keep you alive and to fuel your activity levels.
If they’re broadly equal, you’ll maintain your bodyweight. If you take in more energy than you burn you’ll gain weight (regardless of the combination of macros – i.e. fats, carbs & protein – you’re eating) and if you use more energy than you take in you’ll lose weight.
However, measuring these things accurately can be challenging and our bodies are clever – they like balance – so they employ lots of tactics to try and achieve this in the long term.
If you’ve ever cut calories to try and lose weight (& the opposite is true if you’ve ever tried to gain weight) you may well have found that you lost some weight initially and then things started to plateau. And despite reducing your calorie intake further you struggled to keep losing weight.
This is typically because of a couple of things:
(1) most people reduce their carb intake when trying to lose weight, and as carbs help you to retain water (carbohydrates) the initial weight loss is typically water loss, not fat loss.
(2) the body is programmed to preserve fat in a famine (or calorie deficit) because it’s essential for life and brain function. And if you drop your calories too low your body notices and you tend to lose muscle tone instead as that’s less essential to your body.
(3) Non-exercise activity thermogenesis (“NEAT”) is movement in daily life that isn’t exercise, so things like moving around your house or workplace, playing with the kids, going shopping, fidgeting, etc. Some people are able to burn off nearly 700 calories per day in NEAT whilst others burn very little.
When underfed our bodies typically move less to compensate for the lower amount of energy available and so we burn less calories than normal & perhaps aren’t in quite the calorie deficit we thought we were.
(4) Linked to this, our bodies need energy for our brain and organs to work, they need energy for reproduction and fertility, for repair, etc. and our metabolic rate adjusts as our energy intake changes.
Research suggests that the largest decrease in resting metabolic rate happens when diets reach 1000-1200 calories (or fewer) per day. So again, cutting calories too low typically results in us expending less calories too and can be damaging to things like our menstrual cycle, hormones and general metabolic functions.
Reducing your calorie intake by 10-15% tends to be fine, but much more than that and your body will notice!
So next time you want to lose a few lbs (or more), please focus on doing so in a more sustainable way, with less dramatic calorie decreases so that the process achieves what you want and is sustainable in the long term.
The best place to start would be becoming more aware of your current habits and calorie intake, noticing your body’s hunger & fullness cues and then focusing on eating quality food, more mindfully and stopping when you’re full.