Time to lose 5 BMI points
For most people, the BMI thresholds for normal weight, overweight and obesity increase in steps of 5. BMIs below 25 (and above 18.5) are classed as normal weight, below 30 as overweight and below 35 as obesity.
If you have overweight or obesity, that means you can move into the lower BMI classification simply by losing 5 BMI points. Most people losing weight have a specific weight goal in mind, but you may also have a specific BMI goal you are aiming for.
You might think that losing 5 BMI points will depend on your starting weight, but in fact it only depends on your height. To use our table above, simply find the row corresponding to your height. You'll find two numbers: one for losing 1 lb a week (500 calorie deficit) and another for losing 2 lb a week (1,000 calorie deficit).
If you maintain your calorie deficit over the specified number days, you will lose 5 BMI points, guaranteeing you reduce your BMI category from overweight to normal weight, or from obese to overweight, for example.
What is BMI?
BMI stands for “Body Mass Index“. It is a widely used method to assess whether a person has a healthy body weight. It is a simple calculation based on your weight and height. You can use the number produced by this calculation to compare your personal BMI against the standard reference ranges used by healthcare professionals.
The World Health Organization (WHO) categorize BMI using the following ranges:
- Below 18.5 – Underweight
- Between 18.5 and 24.9 – Normal weight
- Between 25.0 and 29.9 – Pre-obesity (overweight)
- Between 30.0 and 34.9 – Obesity class I
- Between 35.0 and 39.9 – Obesity class II
- Above 40 – Obesity class III
To calculate your BMI, use Gym Geek's BMI calculator. Or, if you have a specific goal BMI in mind and want to convert it back to a weight goal, try our ideal bodyweight calculator.
BMI Formula
The Body Mass Index (BMI) formula is simple calculation to assess whether you have a healthy weight. The formula for calculating BMI is:
BMI = Weight (kg) / [Height (m)]2
The formula takes your weight in kilograms and divides it by your height squared.
How to calculate time to lose 5 BMI points
Reversing the above BMI formula, we can find a formula for a person's starting and goal weight like so:
Starting Weight (kg) = [Starting BMI] x [Height (m)]2
Goal Weight (kg) = [Starting BMI - 5] x [Height (m)]2
Now, assuming you want to lose 1 kg per week, we can simply subtract your Goal Weight from your Starting Weight. Doing this results in this simple formula:
Weeks To Lose 1 kg = 5 x [Height (m)]2
Notice that the formula only depends on your height, rather than your weight. That means it takes the same amount of time to lose 5 BMI points regardless of your current weight.
However, if you plan to lose weight over an extended period of time, don't forget to re-calculate your calorie goal as this number will reduce over time as your weight decreases.
Benefits of losing 5 BMI points
Losing 5 points of BMI can represent a large amount of weight loss. For someone measuring 5'8" in height, 5 points of BMI corresponds to 33 lb of weight.
Provided you are overweight or obese, losing weight can have a positive impact on your overall health, reducing the risk of heart disease and stroke, type 2 diabetes, osteoarthritis and many kinds of cancer. Additionally, losing weight can improve your mobility, energy levels and even your mental wellbeing.
Limitations of BMI
However, it's important to know that BMI is an broad indicator of health status, and it does have some limitations. BMI is calculated based on your height and weight only, and it doesn't make any distinction between weight from muscle and weight from fat.
If you have a high muscle mass, you may have a high BMI and be categorized as overweight or obese. Athletes and individuals who participate in strength training or other sports that contribute to muscle growth often have higher BMIs.
Do taller people lose weight faster than shorter people?
In terms of weight specifically, no. In fact, taller people and shorter people lose weight at the same rate if they maintain the same calorie deficit relative to their TDEE. If you have a deficit of 500 calories per day, you're on track to lose 1 pound a week, regardless of your height.
However, because shorter people have lower basal metabolic rates (BMR), they might find it more difficult (or impossible) to maintain the same calorie deficit as a taller person. In practice, then, taller people could have the advantage.
It may take longer to reach goal weight
Where taller people have a disadvantage is how long it takes to reach goal weight. Because taller people carry more bodyweight, the difference in current weight and goal weight is larger than it would be for a shorter person. This means it could take a longer period of time to lose weight for a taller person.
Thinking of it another way, it takes longer for a taller person to reduce their BMI from 30 to 25, say, than it would for a shorter person. In fact, it takes much longer. A 5'4" person could lose that weight in 204 days, while a 6'2" person takes 272 days to achieve the same BMI goal. That's over 2 months longer!
How long to reduce BMI from 45 to 40?
Reducing your BMI from 45 to 40 changes your weight category from Obesity Class III to Obesity Class II. The average 5'4" woman can reduce her BMI from 45 to 40 in 15 weeks if she loses 2 pounds per week, and 30 weeks if she loses 1 pound per week. The average 5'10" man can achieve the same goal in 17 weeks if he loses 2 pounds per week, and 34 weeks if he loses 2 pounds per week.
How long to reduce BMI from 40 to 35?
Reducing your BMI from 40 to 35 changes your weight category from Obesity Class II to Obesity Class I. The average 5'4" woman can reduce her BMI from 40 to 35 in 15 weeks if she loses 2 pounds per week, and 30 weeks if she loses 1 pound per week. The average 5'10" man can achieve the same goal in 17 weeks if he loses 2 pounds per week, and 34 weeks if he loses 2 pounds per week.
How long to reduce BMI from 35 to 30?
Reducing your BMI from 35 to 30 changes your weight category from Obesity Class I to Pre-obesity, also known as Overweight. The average 5'4" woman can reduce her BMI from 35 to 30 in 15 weeks if she loses 2 pounds per week, and 30 weeks if she loses 1 pound per week. The average 5'10" man can achieve the same goal in 17 weeks if he loses 2 pounds per week, and 34 weeks if he loses 2 pounds per week.
How long to reduce BMI from 30 to 25?
Reducing your BMI from 30 to 25 changes your weight category from Pre-obesity (overweight) to Normal Weight. The average 5'4" woman can reduce her BMI from 30 to 25 in 15 weeks if she loses 2 pounds per week, and 30 weeks if she loses 1 pound per week. The average 5'10" man can achieve the same goal in 17 weeks if he loses 2 pounds per week, and 34 weeks if he loses 2 pounds per week.
References
World Health Organization. (2010). A healthy lifestyle – WHO recommendations. World Health Organisation. https://www.who.int/europe/news-room/fact-sheets/item/a-healthy-lifestyle—who-recommendations
