How Much Weight Will I Lose with RNY Gastric Bypass Surgery

Gastric Bypass Surgery is one of the most well-known and widely used weight-loss surgeries available. It is FDA approved, but it was also at one point the “gold standard” of bariatric surgery. The gastric bypass (RNY) works by creating a pouch from the stomach (becoming the new stomach) and reroutes the small intestine to the new stomach pouch.

Although highly effective, the gastric bypass offers different results – but here are the average number of pounds you can expect to shed with gastric bypass surgery.

How to Project Your Expected Weight Loss?

To find out how much weight patients will lose, let’s look at the average weight loss of the surgical procedure of the gastric bypass surgery in Tijuana, Mexico. Since different people have different heights and weights, they have different BMI or body mass index.

We cannot measure the expected weight loss in total pounds, although patients can calculate their desired weight loss. Someone who is 6 feet 2 inches and 400 pounds will lose another weight than the 5 feet 4 inches and 220 pounds. But these two patients will yield a similar percentage of their excess weight.

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Calculate Your Expected Weight Loss After RNY Gastric Bypass

You will need the formula to start calculating the expected weight loss. Follow steps 1 to 4 and you should have the expected weight loss calculated in a few minutes.

Ideal Weight Loss with Gastric Sleeve Surgery

Ideal Body Weight Chart

Step 1: Your Ideal Body Weight

There are some common ways to calculate the ideal weight. However, the chart below shows the ideal weight for males and females of different heights with different frame sizes.

Step 2: Maximum Weight You’ll Lose*

Current Weight – Ideal Weight = Excess Weight

Step 3: Calculate Expected Weight Loss

Excess Weight x .70 = Expected Weight Loss

Step 4: Calculate Your New Weight

Current Weight – Expected Weight Loss = New Weight After Surgery

Expected Weight Loss with Gastric Bypass Surgery

Regardless of the weight loss you choose, you may expect to lose a certain amount of weight from bariatric surgery in Tijuana, Mexico. This calculator will tell you how much weight you can expect to lose with gastric bypass and each bariatric procedure. Also, determine what you can expect to weigh two years after surgery. Calculations are based on average weight loss per process. To lose the average weight, you will need to follow your surgeon’s preoperative and postoperative guidelines.

We analyzed postoperative weight loss of gastric bypass recipients based on a 2022 survey. Here we showcase the 3-month, 6-month, and 1-year breakdown of over 900+ past patients’ expected weight loss (lbs).

Mini Gastric Bypass Monthly Average Weight Loss
RNY Gastric Bypass Monthly Average Weight Loss
How Much Weight Will I Lose with Gastric Bypass - Excess Weight Loss Timeline Chart

Average Weight Loss with Gastric Sleeve Surgery

What are the Factors That Affect How Much Weight I Lose?

The amount of weight you will lose with gastric bypass surgery depends on several factors. These factors include nutrition, exercise, lifestyle, and total commitment to changing old habits.

  • Nutrition and diet
  • Exercise and physical activity
  • Lifestyle changes
  • Bariatric vitamins
  • Commitment to change old habits
  • Age
  • Body size and type
  • Genetics

Other Variables Impacting Weight Loss

The bariatric surgeon’s knowledge, technique, and expertise can differ your weight loss results.

For example, how well the surgeon makes the new pouch and how much restriction it creates are significant factors in losing weight and maintaining it. Apart from the surgeon and team, more factors after surgery can affect the success rate of gastric bypass and its single-loop version mini gastric bypass surgery.

Suppose you do everything correctly after gastric bypass surgery or mini gastric bypass surgery. You’ve changed your diet (gastric bypass makes some dietary changes, which is why the gastric bypass creates more weight loss than most other procedures), you regularly exercise, and you try to sit less and be more active. How long will you stay motivated when everything is said and done?

How Much Weight Will I Lose with Gastric Bypass Surgery RNY

Diet and Exercise

Long-term diet and exercise changes and other habit changes can result in weight loss that exceeds the average values used in these calculations.

Remember that 70% is the average weight loss of past gastric bypass patients. Some people lose less, and others lose much more. In the end, the success of a gastric bypass sets the appropriate expectations, decides to change your habits, and adheres to those decisions.


If your number looks lower than expected, do not feel defeated. People are surprised that they can not expect to go from 250 kilograms (551 pounds) to 120 kilograms (264 pounds) with bypass surgery alone. Gastric bypass is not a quick fix but will reduce your weight to slightly easier handling. When weight falls, it becomes easier to exercise, stay longer, enjoy life, and continue to lose weight.

The hardest part is losing the first 50 kilograms or 110 pounds. When you begin to notice the results, this will motivate you to lose more, eat healthier, boast about your friends, and show your fantastic progress. Good luck!