Gastric Bypass Weight Loss Chart and Timeline

gastric bypass weight loss chart
This post will answer popular questions like “What is the average weight loss with the gastric bypass?”, “How much weight do you lose the first month after gastric bypass?” and “Do you lose more weight with the gastric bypass?” We have also included a gastric bypass weight loss chart to give you an overview of what to expect.

Because gastric bypass surgery is one of the most performed procedures and has been around for about 50 years, we have the benefit of access to a large amount of statistical data including success rate, weight loss patterns, and complications after gastric bypass.


What Is Gastric Bypass Surgery?

Roux-en-Y or gastric bypass surgery is a technique used when performing weight loss surgery for people with body mass index levels between 35 to 40 and higher. Many individuals also have serious health issues that are caused because of their excess weight and the surgery helps to alleviate these.

The surgeon reduces the size of the stomach by shaping it into a small pouch and attaching it directly to the small intestine. When the patient eats, the food will go into the small pouch and then directly into the small intestine instead of lingering in the stomach to be digested and passed through the entire digestive system.

This will prevent the individual from eating too much food in one sitting as well as prevent the body from absorbing the calories that are ingested.

How Does Gastric Bypass Work?
How does gastric bypass work?

What Is Average Weight Loss with Gastric Bypass?

When undergoing gastric bypass surgery you can expect between a 50-70% loss of your excess body weight. When calculating excess body weight, your body mass index (BMI), height, and current weight are taken into consideration to generate an ideal weight, or the goal weight you are trying to achieve through weight loss.

A healthy BMI is generally considered to be in the range of 18.5-24.9; BMIs in the range of 25 to 29.9 are considered overweight, and anything over 30 is considered obese.

For example, if an individual’s goal weight is 150 lbs but they currently weigh 290 lbs, they are carrying 140 lbs of excess weight. If they were to lose 70% of their excess weight, i.e. 98 lbs, during the first year (now at 192 lbs) and continue their dietary and exercise plan, they would be on track to achieving their ideal weight within 18-24 months.

How To Achieve Your Expected Weight Loss after Gastric Bypass Surgery

Gastric bypass surgery should be considered a tool that you can use from this point forward to help you lead a healthier lifestyle. A tool is something used by someone to assist them in performing a task or function but the tool does not do all the work alone. Have you ever seen a hammer driving nails by itself? Without the hammer, it would be virtually impossible to drive a nail with our human hands. Having the benefit of working together with the tool makes all the difference.

Although you will have ongoing support from your surgeon and the medical staff at the surgery center, the majority of your weight loss success depends on your commitment and determination to follow the program provided to you. Following your dietary restrictions, exercise routines, keeping up with your appointments, and staying plugged into support resources are all vital elements that can make or break your goals to reach your ideal weight.

The best way to achieve your expected weight loss goals after gastric bypass surgery is for you to stay in close communication with your team of experts, follow your plan, and do not ever give up. You can do this!

Video: Patient Testimonial – Gastric Bypass

Jolene's Story - Gastric Bypass Patient Testimonial - IBI Healthcare Institute

Our patient is talking about her experience with the gastric bypass procedure. Learn more about the gastric sleeve procedure:

Do You Lose More Weight with Gastric Bypass Surgery?

The short answer is yes, but the percentage difference between the average amount lost by patients who had gastric bypass vs gastric sleeve is only around 5%. Gastric bypass surgery will usually result in quicker weight loss but data show that at the 24-months point the numbers are pretty similar.

Weight loss potential is greatly impacted by the patient’s determination and perseverance, following dietary guidelines, and increasing physical activity as their weight-loss proceeds.

How Much Weight Do You Lose the First Month after Gastric Bypass?

The first month after gastric bypass surgery patients will lose weight rapidly, which normally provides them with an emotional boost so this period is often called the “honeymoon phase”.

The rapid weight loss can be attributed to the fact that during this month, patients are on a liquid diet, their body is still healing from the surgery, and they are not feeling hungry, so calorie intake is fairly low. Patients still have a high motivation level and are excited to see the weight coming off so fast.

Patients can expect to lose around 17% of their excess body weight during the first month after gastric bypass surgery. A patient who is 5’8’ weighing 250 pounds with an ideal weight of 150 lbs can expect to lose about 17 pounds during the first month. The calculation and terminology are explained in the table below.

Glossary of Terms for Weight Loss Calculations

Definition Sample Patient Data
Current Weight
Patient’s weight at the time surgery is scheduled 250 lbs
Ideal Weight
The goal weight of the patient. Normally obtained from an ideal weight calculator 150 lbs
Excess Weight
Current weight minus ideal weight equals excess weight 250 – 150 = 100 100 lbs

Milestones on the Gastric Bypass Weight Loss Timeline

Results will vary for each patient and will be influenced by their unique characteristics, such as height, starting BMI, health conditions, and age. This is a general overview of expected results if the patient does not deviate from their post-op diet and exercise plan.

Most often, gastric bypass weight loss is categorized in milestones at 3 months, 6 months, 12 months, and 18 months.

Milestone #1 – 3 Months Post-Op

The first three months after surgery will be the time when weight is lost the fastest. Changes made to the digestive system restrict calorie intake and absorption, and the liquid diet perpetuates rapid weight loss. Patients can lose between 30 and 40 pounds, which amounts to approximately 25-35% of their excess weight.

Milestone #2 – 6 Months Post-Op

The rate of weight loss will slow down after about 3 months but most patients continue to lose between 1 and 2 pounds a week during this time. At the end of six months, most patients have lost approximately 45% of their excess weight.

Milestone #3 – 12 Months Post-Op

At the 12-month mark, some patients may be close to their target goal if they have not already met it with between 50% and 60% of their excess weight eliminated. If you have not achieved these percentages at the end of a year, do not worry, stay focused, and continue to persevere, and you will get there. Every individual is different and these results are just an average.

Milestone #4 – 18 Months Post-Op

Average results indicate that patients who have diligently followed their weight loss routine should have achieved their ideal body weight by this time or possibly exceeded it. Most patients reached a 60% level of lost excess weight some even reached 70 to 80% by the 24-month point.

Your weight loss goals can be achieved through the combination of weight loss surgery and your amount of personal determination and perseverance. If you have special circumstances, your surgeon will take these into consideration when creating an estimated weight loss timeline for you.

Gastric bypass weight loss results will vary by individual so do not be concerned if your progress is different as these are only averages.

Gastric Bypass Weight Loss

We have talked about percentages of excess weight loss (EWL) and basic milestone expectations but what does this mean to you as far as how many pounds you’re going to lose? If you have lost 25-30% of your excess weight after three months, how much are you going to weigh at that point?

This gastric bypass weight loss chart should give you an idea of what your weight may look like during the aforementioned milestones. It is important to keep in mind that starting BMI, height, age, gender, and any current health conditions are all factors that contribute to these numbers.

For purposes of illustrating expected weight loss, the calculations in this gastric bypass weight loss chart use a female of an average build who is 5’8” tall. For benchmark purposes, this patient’s ideal or goal weight range would be 145-150.

Gastric Bypass Weight Loss Chart

Please, swipe to the right
to see the entire table
Starting Weight Weight in 3 Months (EWL 30%) Weight in 6 Months (EWL 45%) Weight in 12 Months (EWL 60%) Weight in 18 Months (EWL 65%)
200 lbs 181 lbs 173 lbs 165 lbs 160 lbs
225 lbs 198 lbs 187 lbs 175 lbs 170 lbs
250 lbs 215 lbs 201 lbs 184 lbs 176 lbs
275 lbs 232 lbs 185 lbs 193 lbs 185 lbs
300 lbs 251 lbs 226 lbs 203 lbs 192 lbs
325 lbs 267 lbs 241 lbs 213 lbs 204 lbs
350 lbs 278 lbs 256 lbs 224 lbs 213 lbs
375 lbs 304 lbs 268 lbs 235 lbs 223 lbs
400 lbs 323 lbs 283 lbs 245 lbs 232 lbs

Gastric Bypass Weight Loss Progression Calculator

Use our handy gastric bypass weight loss progression calculator to get an idea of what your weight loss journey will look like along the way. Knowing what to expect will enable you to better prepare for what the recovery and post-op period entails. This calculator uses some key elements to determine how much weight is typical for parameters similar to yours.

If you or your loved one is considering having gastric bypass surgery and would like to learn more, contact IBI Healthcare Institute today for a consultation. The experts at IBI Healthcare Institute are ready to answer your questions and share information with you regarding the options available for weight loss.

We offer both surgical procedures, such as gastric bypass, and also some non-surgical weight loss techniques delivering excellent results. Contact us today for more information!

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