When asked to recommend a “guaranteed” weight loss plan, our reply is that everyone will probably lose weight with a 1500 calorie diet. You will likely lose at least 2 kilograms for the first month you stick to a 1500 calorie diet. The thermodynamic logic of a 1500 calorie diet is straightforward. What’s more, we know from repeated studies that it is generally a healthy target for most people to aim for.
Basic Weight Loss Equation
As we discuss in other articles, weight loss is unfathomably complicated, but also blindingly simple. If you eat more calories than you use through normal body function and extra physical activity, you will gain weight. If you use more calories than you eat, you will lose weight
Fat has about 7600 calories per kilogram, so you will lose approximately 500 grams of fat for every 3800 calories you burn. 3800 calories burned over the course of a week is about 540 calories per day (3800 divided by 7 days). Following this simple logic, you would need to reduce daily calories by 500 to lose about 500 grams per week.
Of course, all other things are not equal because cellular metabolism does not happen in a vacuum. There are a thousand influencing factors related to body composition, metabolism, and hormonal balance. The human body is not a spreadsheet so we cannot use a simple formula to plot an easy graph to accurately predict actual weight loss. However, we know with certainty, there will be weight loss when there is more energy taken out than put in.
In fact we know, from hundreds of studies, that people usually lose about 500 grams in body weight for each week that they reduce their average daily food intake by 500 calories.
We eat more than 1500 Calories per day
It is hard to know exactly how many calories are being absorbed and used by our bodies daily. Luckily, there are convenient methods anyone can use to make good estimates. If your weight is stable, then the energy you are putting in is balancing the energy being taken out. Thus, you can estimate how many calories you eat by measuring the energy going in and out of your body.
In the lab, scientists use sophisticated measurement devices and controlled environmental conditions on closely monitored test subjects to measure calorie intake and expenditure. This level of analysis is far beyond what the everyday person needs.
Instead, you can measure incoming calories by using a tool like our calcount Calorie Tracker to keep a food diary which adds up the total calories in the food you eat. Those food calorie counts are based on average calories in similar foods as measured in the lab by food scientists.
You can measure outgoing calories by applying a credible total daily expenditure formula to your personal body metrics like weight, gender, age, and height. Our calcount Calorie Calculator does exactly that.
Alternatively, you can get an estimate of your calorie consumption by reviewing the findings of large-scale scientific studies. According the Food and Agriculture Organization (FAO), the average daily food consumption in developed countries is between 3200 and 3800 calories (this includes food waste). Our own FSANZ reports that the average Australian eats 2079 calories (8700kJ) per day, based on surveys.
Looking at our own data, the calcount team concludes that we collectively eat a median of 2650 calories per day.
Want to Lose Weight? Use a 1500 Calorie Diet
So why do we often recommend the 1500 calorie daily target? Because we need to consider a few key factors when picking a good general calorie target for a weight-loss diet:
Effective for weight-loss
Perhaps most importantly, we want the calorie target to be at a level where noticeable weight is lost in a reasonably short time. Since we know that most of us are eating more than 2000 calories per day, and that a calorie deficit of 500 calories per day causes effective weight loss, then a target of 1500 calories becomes a compelling proposition (2000 minus 500). In theory, you will probably lose at least 2 kilograms for the first month you stick to a 1500 calorie diet. In practice, you will lose more or less than this, depending on your personal circumstances.
If by chance you are already eating 1500 calories or less per day and still want to lose weight, please see a doctor for medical advice.
Safe for most people
Given the enormous number of personal attributes and health conditions you may have, no general advice or information could replace the professional guidance of your own doctor. However, based on available published research, 1500 calories per day is an accepted healthy target for most people. Consider that a typical so-called “starvation-diet” or VLCD (Very Low-Calorie Diet) has a daily target of about 800 calories. According to many sources, the average healthy person normally eats 2000 calories. In some extreme cases, doctors actually recommend VLCDs. The mid-point between the VLCD and a 2000 calorie diet is 1400 calories, so 1500 calories cannot too low of a target. At 1500 calories, provided your diet includes all the recommended micro-nutrients, you will be fine.
Achievable with effort
Make no mistake, for people accustomed to eating north of 2800 calories per day, a 1500 calorie diet is hard, very hard. However, there are some tried and tested methods to make it easier to cope with. Some people can achieve a necessary reduction in calories by simply downsizing their portions by swapping regular plates and bowls for smaller ones. Others find that changing their food mix from carb-heavy to protein-heavy does the job. Yet others take up the challenge by trying whichever diet trend happens to be popular now. Suffice to say that the 1500 calorie diet comes in many different forms, some of which are suited to just about everybody.
Ideally, with specific meal plans, regular check-ins, calculated exercise, and tailored mental coaching anyone can home in on a desired body weight goal. Unfortunately, the type of intense professional attention that highly specific nutrition and exercise programs require usually put them out of reach for normal people. Instead, the average person needs an easy-to-grasp concept to motivate practical action.
A 1500 calorie diet is a single fixed point target which a person can focus on for the duration of their mission to lose weight. Stay on it for weight loss, then come off it when the desired weight goal is reached. Switch macro-nutrients and portion sizes and meal timing around randomly to prevent boredom and to stimulate beneficial hormonal cycles. Rinse and repeat until lifestyle habits change to the point where weight stabilises at a healthy level.
How about 1600 calories?
Yes, you will lose weight on a 1600 calorie diet. You will also lose weight on a 1400 calorie diet. Hence, 1500 calories is a good daily calorie target, because it is between the “hard” and “less effective” calorie counts. In practice, if you aim for 1500 daily calories, you will eat between 1650 and 1450 calories per day. Done consistently, this will be enough of a deficit to let you see real progress over a few weeks. At a 1600 calorie target, the average daily deficit will be smaller, but still effective enough to see real progress.
Of course, this assumes that you are currently in the habit of eating more than 2000 calories per day. You can get a more exact understanding of what an individual target looks like by using the calcount Calorie Tracker.
You will lose weight on a 1500 calorie diet if you stick to it for at least 3 weeks. This is because you will be creating a calorie deficit of about 500 calories per day. If you burn 500 calories per day, you will lose about 500 grams of body weight per week. Provided that you are generally healthy and eat a balanced diet, the 1500 daily calorie target is safe and effective.