You’re sweating it out on the treadmill or around the block, with the mile and calorie counters pushing you to keep running. Your old pair of jeans finally fit you again, and all those times you resisted eating late-night snacks become worth the effort. You look in the mirror one morning and admire your slimmer and toner arms, and the aches and pains of your planks, push-ups, and weight-lifting no longer seem like torture.
Having a healthier lifestyle for weight loss is not as easy as turning on a switch; ditching your unhealthy habits is not as easy as turning off a switch. The first few days and weeks are usually the hardest, and committing to making healthy changes day in and day out will be hard more often than they’re not.
Perhaps if you understood what happens to your body when you lose weight, you’ll be more motivated to run that extra mile, keep your pantry stocked only with healthy foods, and do ten more reps, especially when you’re tempted to “take a break” from your weight-loss plan.
So what does happen to your body when you lose weight?
What is Lost When You Lose Weight?
During the first week or so, the weight you lose is mostly water weight. This is especially the case when the weight loss is significant – more than 3 pounds. If you’re following an intense exercise regimen or on a low-carb diet and there are fewer calories readily available (from the food you eat) than what your body needs for energy, your body uses up its glycogen stores (its fuel reserve). Metabolizing glycogen for fuel requires a lot of water.
If you keep up your workout routine and/or diet for many months, or even longer, and especially if you aim for slow but consistent weight loss, you will be losing your excess fat.
However, if you’re only dieting and not exercising or only exercising minimally, and particularly if you’re on a highly restricted diet that is low in both carbs and protein, your body will eventually metabolize your muscles, because this is where glycogen is also stored. Remember that before the body starts using up its fat stores for energy, it will use up its glycogen stores first.
Losing muscle mass will lead to the slow-down of your metabolism, and this means that your weight loss will plateau sooner or later.
This is why it’s important to combine exercise and diet when on a weight-loss plan. Strength-training exercises, in particular, should be part of any workout regimen. When you’re also building muscles, your body will require even more fuel so it will burn the extra fat in your fat cells. Muscle recovery and growth also keeps the metabolism up for many hours after your workout.
Typically, you will lose fat wherever most of your excess weight is. For example, women commonly start losing extra fat from the lower part of their body first because it’s where most of their excess weight is.
Another reason why you should have a regular exercise routine is that fat loss does not affect metabolism. On the contrary, the hormones that control hunger are actually kicked into higher gear when you’re losing weight. If you want to sustain your weight loss and, once you reach your goal, to maintain your ideal weight, you will have to maintain your body’s calorie deficit through both exercise and a healthy diet.
What Happens to Your Metabolism?
It’s important to know that your body will always work to achieve and maintain homeostasis, a state of balance which ensures that all systems are functioning at maximum efficiency.
During the first few weeks of your weight-loss plan, your body makes up for the decreased energy input (from a restricted diet) and/or increased energy output (from exercise) by tapping into its energy reserves – first from glycogen, and then from fat – to ensure that it will be able to support all physiological processes and physical activities based on your previous “normal set point” for calorie input and output.
If you maintain the same level of calorie deficit, your body will eventually adapt by adjusting your metabolism accordingly, setting a new normal calorie input and output requirement.
If you’re only dieting, for example, your metabolism will slow down to conserve energy – this means burning fewer calories based on the decreased calorie input so that your body won’t need to tap into your fat stores for energy, which means you’ll stop losing weight. If you’re exercising, your metabolism will also level off after its initial increased rate when it learns how much energy you need to sustain your new activity level. Your body will adjust its calorie output so that you will only be burning the exact amount of calories you need for your activity level, and, again, your weight loss will plateau.
This is why exercise should be combined with a weight-loss diet. At the same time, you should vary the frequency and intensity of your workout routine and give your body adequate rest in between. To keep your metabolism using more energy than you consume, you need to keep your body guessing so that it does not simply settle into a new normal calorie input and output level.
What Happens When You Lose Weight – Final Thoughts
Weight loss is usually a difficult process. You have to work at it every single day to achieve your weight-loss goal and then to maintain it. It also takes a lot of work to make healthy choices second nature. But understanding what happens to your body when you lose weight should help making the necessary lifestyle changes more manageable.
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