When it comes to underlying principles of weight loss, there is no difference between trying to lose a kilo or two for cosmetic reasons and losing 10kg due to health concerns. In either case, the same factors are responsible both for the exact amount you’ll lose and the time it will take you to achieve your goal. In order to understand how to effectively lose weight, one should be familiar with these principles.

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Our body weight is influenced primarily by two factors – the amount of energy we take in through food and beverages and the amount of energy we expend during the day. Naturally, the imbalance between the two leads to changes in weight, increasing it if the energy input is larger than energy expenditure and vice versa. In this context, energy is measured in calories, allowing us to precisely quantify the amount of energy involved in our metabolic processes. So, if you’re wondering how to lose weight, the core of the answer is finding a way to decrease your caloric intake, while simultaneously increasing the number of calories you burn each day.

However, one should keep in mind that increasing the expenditure of calories might not always be necessary. In fact, for most cases, especially if your weight loss concerns are related to aesthetical appearance, simply cutting down on caloric intake might be enough to do the trick, although increasing the amount of energy spent daily could make the process faster.

Basal metabolic rate

This is where basal metabolic rate (or BMR for short) comes into play. In more scientific terms, BMR is the rate of energy expenditure per unit of time by endothermic animals at rest and when all environmental factors can be considered neutral.1 However, in layman terms and specifically related to the question of how to lose weight, BMR can be thought of as amount of energy needed by the body for its necessary biological functions, without any additional expenditure, meaning the energy consumed by the body at rest, without any physical or psychological stress. So, our bodies burn calories every day without any effort on our side, but this rate might not be enough if you’re looking for quicker results.

So, the best way to lose weight is to achieve the optimal ratio between caloric intake and expenditure. Energy intake is completely controlled by the individual since it’s determined by the amount of food we consume each day, as well as by the energy stored in the food (its caloric value). So, by making informed decisions about changes in our diet, we can easily control our caloric intake.

On the other hand, our energy expenditure is determined by our basal metabolic rate which we cannot directly affect, as well as our physical activity. However, one should keep in mind that there are some medical conditions which might introduce a deviation from the expected BMR in which case, before giving any weight loss method a go, consultations with a doctor are absolutely necessary.

Daily energy expenditure

Another important factor determining the total energy expenditure is body weight itself and it is helpful to think of this when planning how to lose weight. Countless studies, as well as the basic principles of thermodynamics, show us that the greater the body weight, the more calories are needed to keep it in its present state. Or, in other words, it takes more calories to keep your weight at 90Kg than to keep it at 70Kg. It is precisely because of this fact that in most cases, just cutting down on calorie intake is enough for noticeable weight loss. By doing so, one simply makes the body unable to keep its weight with the current caloric intake, so the weight will slowly begin to drop.

However, the rate of weight loss will significantly vary depending on your lifestyle. For example, people whose job involves physical labour will naturally burn more calories than people who spent most of their time sitting at the desk. If you are aware of the sedentary nature of your job, introducing physical activity, such as exercise, in your daily routine might be the best way to lose weight. And even if you are getting enough physical activity, but want to lose weight fast, adding a bit extra effort might do the trick. However, one should always be careful not to overdo it and ensure that physical activity remains beneficial for the health and not have an adverse effect. To ensure this, it is best to consult with a doctor or a personal trainer.

The “no-diet” approach

All this information is useful for understanding the underlying mechanisms of both weight loss and weight gain, but when you’re planning how to lose weight fast, the question that really interests you certainly is – what is the exact calorie to kilogram ratio?

The short, albeit imprecise answer to this question, would be that one kilogram of body weight is equal to around 7,700 calories. Ideally, this means that, for example, if you have excess of 1,100 calories every day, it would take you seven days to gain one kilogram. And, the opposite is also true – a daily deficit of 1,100 calories would mean weight loss of one kilogram in a week.

However, in reality, a variety of factors make this kind of precise calculation impossible. You cannot know for certain the exact amount of calories in every meal and snack, or how much calories have you burnt by walking to work instead of taking the bus, for example. But still, this ratio can serve as a rough guide in your weight loss process.

The best way to lose weight, according to many, is to balance the deficit of calories. Especially if you’re looking to lose weight for purely aesthetical reasons, you can even achieve this with the so-called no-diet approach. Let’s take the already mentioned example. If you aim to lose a kilogram within a week, it would be healthier to cut your caloric intake by 550 calories and aim to burn additional 550 through physical activity than to cut your intake by whole 1,100 calories. By balancing intake and expenditure, you can, for example, substitute unhealthy snacks with healthier alternatives and on top of that, introduce a moderate amount of physical activity. In this way, there won’t be any significant strain on your body.

Although it doesn’t sound like much, if you’re still working out how to lose weight, it might be helpful to remember that some activities which won’t even be classified as exercise can burn a significant amount of calories. For example, a brisk walk of 45 minutes will burn around 300 calories, while the same time spent on house chores can burn up to 200 calories and on mowing the lawn 275 calories. So, burning calories can be as simple as introducing these minor changes in your lifestyle – walking instead of taking the bus or a car or cleaning the house on a regular basis. Combined with some minor modifications of your dietary choices, these activities can produce visible results in an unexpectedly short amount of time.


In scientific terms, diet is the sum of food consumed by an organism. However, for those interested in the best ways to lose weight, diet is usually a shorthand for weight loss diet, method related to dieting – the practice of eating food in a regulated or supervised fashion in order to decrease, maintain or increase body weight.2

It is easy to see why people might be interested in trying out different types of weight loss diets. For one, the regulated dietary choices make control of caloric intake significantly more precise and reliable than in no-diet approach. Also, for those whose jobs include little to none physical activity and leave little spare time, exercise and other types of physical activity might be a luxury they can’t afford due to their tight schedule, so their weight loss efforts might be focused primarily on limiting caloric intake and energy expenditure only secondary, if at all. The same goes for more severe cases of obesity, where physical activity is strictly limited by the condition, so caloric intake is of primary concern.

There are numerous types of weight-loss diets like low-fat, low-carb or low-calorie. The choice of the diet is most of the time determined by numerous factors which include the nature of your condition, physical fitness, genetic predispositions, the amount of weight you wish to lose, other medical conditions and complications et cetera. While there are some general guidelines which can be used to determine the optimal diet for your specific case, it is still highly recommended that you discuss this question with your doctor or nutritionist for optimal and long-term results.

Weight-loss pills

For those looking for best ways to lose weight, weight-loss pills often look like a good alternative to long-lasting and unreliable diets or exhausting exercise. While this might be somewhat true, it is important to note that weight-loss pills can rarely produce desired results without accompanying lifestyle and dietary changes. So, this method should be thought of more as an aid to weight-loss process than a stand-alone method. The most effective weight-loss medications, such as Xenical or Alli, work by inhibiting the absorption of fats from the food, thus reducing caloric intake. Usually, this mechanism of action is supplemented by doctor-supervised low-calorie diet to ensure safe treatment and noticeable results.

Bariatric surgery

Bariatric surgery or weight loss surgery is certainly an option for those looking how to lose weight fast. It includes a variety of procedures performed on people in order to reduce the size or capacity of the stomach and thus reduce the perceived hunger, allowing people to eat significantly less food, without feeling hungry. While certainly effective both in short-term and long-term weight loss, bariatric surgery is often viewed as a last resort. It certainly isn’t meant for those who are mostly interested in losing weight due to cosmetic considerations, but for those whose obesity poses a significant threat to their health and wellbeing. The medical community agrees that bariatric surgery is recommended only for obese people with a body mass index greater than 40 or people who have other serious medical condition such as diabetes and BMI of at least 35.


  1. Basal Rate of Metabolism – University of Chigaco
  2. Diet in the Management of Weight Loss – CMAJ Group