Excess Weight Loss: Get to Know the Metric

A number on the scale tells you the total weight, but it doesn't tell you the context. It doesn't account for where you started or how much you actually need to lose to be healthy.

This is why medical professionals, especially in the world of weight loss surgery, don't focus solely on pounds lost. They use a different tool. They look at excess weight loss (EWL).

If you are researching bariatric surgery or serious medical weight management, you have probably seen this term. It is often abbreviated as EWL. It is the most honest way to track progress because it levels the playing field. It changes the conversation from "how much do I weigh?" to "how much of the problem have I solved?"

Here is everything you need to know about this metric.

What Is Excess Weight Loss?

To understand this metric, you have to look at your body weight in a specific way and divide your total weight into two separate piles.

The first pile is your ideal body weight. This is the weight that medical charts suggest is healthy for your height. It is the weight you would be if your Body Mass Index (BMI) was roughly 25. This is the weight your body "needs."

The second pile is your excess weight. This is simply the extra weight, the pounds you carry above that ideal number. When doctors talk about excess weight loss, they are measuring how much of that second pile you have managed to eliminate.

This distinction is important because if a surgeon tells you that a gastric sleeve procedure typically results in "60% excess weight loss," they are not saying you will lose 60% of your total body weight. They are saying you can expect to lose about 60% of that extra fat that  you are carrying.

Excess Weight Loss is also a measure of efficiency. It tells you how effective a diet or surgery is at attacking the fat stores that are actually affecting your health.

How to Calculate It

Take a calculator and let’s figure this out. You just need to know your current weight and your height.

Take these three steps:

1. Determine Your Ideal Weight

First, you need a baseline. Most medical calculators use a BMI of 25 as the cutoff for a "healthy" weight. You need to find the weight that gives you a BMI of 25.

For this example, let's use a hypothetical person named John.

• John is 5 feet 9 inches tall.
• Based on standard charts, a BMI of 25 for a man of his height is approximately 169 lbs.
• This is John's Ideal Body Weight.

2. Find the Excess Amount

Next, you find out how much extra weight John is carrying. Let’s assume John currently weighs 280 lbs.

You simply subtract the ideal weight from the current weight.

• Current Weight: 280 lbs
• Ideal Weight: 169 lbs
• Math: 280 - 169 = 111 lbs

John has 111 lbs of excess weight. This is the number that matters for the calculation.

3. Calculate the Percentage

Now, imagine John has surgery or goes on a strict diet plan. Six months later, he steps on the scale and weighs 220 lbs.

He has lost 60 lbs total (280 minus 220).

To find his Excess weight loss percentage, you divide the amount lost (60) by the excess weight (111) and multiply by 100.

• 60 divided by 111 equals 0.54.
• 0.54 multiplied by 100 is 54%.

So, John has achieved 54% excess weight loss.

Even though he is still technically "overweight" at 220 lbs, looking at it this way shows he has eliminated more than half of his excess weight. That is a massive success.

Why This Metric is Better Than BMI

People often get frustrated with BMI (Body Mass Index). It feels vague. It doesn't tell the whole story. Excess weight loss is generally considered a better metric for tracking personal progress for a few reasons.

It validates the effort of heavier patients.

If you start at 400 lbs, losing 20 lbs might not even change your pant size. It can feel discouraging. But when you calculate that as a percentage of your excess weight, you see the needle moving. It provides a psychological boost that raw numbers sometimes hide and that is so needed on a weight loss journey.

It creates a fair comparison.

This allows doctors to compare results between different people. A 5-foot woman losing 50 lbs is a much bigger deal medically than a 6-foot-4 man losing 50 lbs. By looking at the percentage of excess weight lost, doctors can see that the woman likely solved 80% of her weight issue, while the man might have only solved 30%. It standardizes the results.

It sets realistic expectations.

This is the most practical reason to use it. If you go into weight loss surgery thinking you will end up looking like a fitness model, you will probably be disappointed. Most surgeries do not result in 100% excess weight loss. Knowing that 60% or 70% is the standard for success helps you set goals that are actually achievable.

Real World Benchmarks: What is "Good"?

If you are looking at this metric, you probably want to know what a good number is.

In the medical community, specifically regarding bariatric surgery, an operation is usually deemed "successful" if the patient achieves at least 50% excess weight loss.

Different procedures have different averages. While individual results vary wildly based on lifestyle and genetics, here is what the data generally shows for one year post-surgery:

• Gastric Banding: Patients often see between 40% and 50% excess weight loss.
• Gastric Sleeve (Sleeve Gastrectomy): This usually results in 60% to 70% excess weight loss.
• Gastric Bypass: This is often higher, ranging from 70% to 80% excess weight loss.

If you are trying to lose weight through diet and exercise alone (without surgery), these numbers are harder to hit, but even small percentages matter. Losing just 10% to 20% of your excess weight can have a profound effect on sleep apnea, high blood pressure, and joint pain. You don't need to hit 100% to get your health back.

The Difference Between TWL and EWL

When you read medical studies or browse health forums, you will see two acronyms that look similar but mean different things: TWL and EWL.

TWL stands for Total Weight Loss. This is the percentage of your total body mass that is gone. If you weigh 200 lbs and lose 20 lbs, that is 10% total weight loss. It is a simple, raw calculation.

EWL stands for excess weight loss. As we discussed, this is the percentage of the extra weight that is gone.

Here is why the distinction matters: In a clinical trial, a new drug might claim to produce "15% weight loss." They usually mean Total Weight Loss. A surgical center might claim "70% weight loss." They almost always mean excess weight loss.

If you don't know the difference, you might think the surgery is only 4 times more effective than the drug, but the math is actually much more dramatic than that. Always check which metric is being used so you don't get confused by the data.

A Note on Accuracy and Limitations

While excess weight loss is a helpful tool, it isn't perfect. It relies heavily on the definition of "Ideal Body Weight."

The charts used to determine your ideal weight are old. They don't know if you are an athlete with dense muscle or someone with a very light frame. If you are a naturally muscular person, the charts might say your ideal weight is 170 lbs, but you might be perfectly healthy and lean at 190 lbs.

In that case, the formula calculates your "excess" based on a number you shouldn't actually be trying to reach. It might say you have 50 lbs of excess weight when you really only have 30 lbs of fat to lose. This skews the percentage.

So, while it is a great metric for tracking major changes, don't treat it as a strict law. It is a guideline.

A New Way Of Looking At The Bigger Picture

Excess weight loss is a way to look at the bigger picture. It stops you from obsessing over every single pound and helps you focus on the proportion of the weight that is actually affecting your health.

Whether you are considering surgery or just trying to get a better handle on your health journey, knowing this number puts you in control and helps you understand that success isn't about reaching a "perfect" number on the scale, but about significantly reducing the burden your body is carrying.

FAQ

What is the difference between Total Weight and Excess Weight?
Total weight is the simple number you see on the scale. Excess weight is the specific amount of weight you are carrying above your medically "ideal" weight (calculated using a BMI of 25).

How do I calculate my Excess Weight Loss (EWL) percentage?
You can calculate it in three steps:

1. Find your baseline: Determine your ideal weight based on a BMI of 25 for your height.
2. Find the excess: Subtract that ideal weight from your starting weight.
3. Calculate the percentage: Divide the amount of weight you have lost by your excess weight, then multiply by 100.

What is considered a "successful" EWL percentage?
In the medical community, specifically for bariatric surgery, achieving at least 50% excess weight loss is considered a success. You do not need to hit 100% to see massive health benefits regarding sleep apnea, blood pressure, and joint pain.

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