The gastric bypass operation has been proven over 40+ years to be highly effective for weight loss. Amount of gastric bypass weight loss, however, varies between different surgeons/programs. Read below about our gastric bypass weight loss statistics, and about how our results compare to what’s reported in the published gastric bypass literature.

Gastric Bypass Weight Loss

Before discussing weight loss results, it is important to understand how weight loss after surgery is described.

The most common way to describe weight loss after surgery is by percent of excess weight lost (%EWL). Excess weight is the amount of weight over ideal weight. Ideal weights are derived from the Metropolitan Life Insurance Company height/weight tables. See the table at the bottom of this page for a tabulation of ideal weights.

Gastric Bypass Weight Loss – Our Results

Orange County bariatric surgeon Dr. Oliak has performed >1000 gastric bypass operations since starting his career in 2002. His gastric bypass weigh loss statistics are as follows: average 78% EWL (excess weight loss) at 2 years after surgery, average 72% EWL at 5 years after surgery, and average 66% EWL at 10+ years after surgery.*

Dr. Oliak’s gastric bypass weight loss statistics compare favorably to the industry averages (see table and discussion below). In Dr. Oliak’s experience, high-quality surgery and patient care (education, follow-up, support) are necessary for achieving better-than-average gastric bypass weight loss results.
Our gastric bypass program


Our Gastric Bypass Weight Loss Statistics

76% EWL after 1 year

78% EWL after 2 years

75% EWL after 3 years

72% EWL after 5 years

74% EWL after 7 years

66% EWL after 10-13 years

* The weight loss results above are averages. Individual patients can lose more or less weight than the average.
Our %EWL (percent excess weight loss) statistics are for all gastric bypass operations (>1000) completed 2002-2017.

Our Gastric Bypass Weight Loss Statistics Compared to Published Literature

Time after surgery

Dr. Oliak’s %EWL*

Published literature %EWL

2 years

78%

68%*

3-5 years

73%

65%*

10 years

65%

55-59%*

* The weight loss results above are averages. Individual patients can lose more or less weight than the average. Dr. Oliak’s %EWL (excess weight loss) statistics are for all gastric bypass operations (>1000) completed 2002-2015. Published literature %EWL statistics are from Livingston et al for 2yr and 3-5yr data, and from Pories et al, Obeid et al, and Higa et al for 10yr data.


Gastric Bypass Weight Loss – Published Studies

There have been 100s of studies published on gastric bypass weight loss, by 100s of surgeons. The quick summary of the published literature is that gastric bypass surgery is highly effective for weight loss, but the amount of average weight loss varies depending on the surgeon and program.*

Because the published studies are quite variable in what they report, several researchers have published review studies. Review studies compile data from numerous other studies to get a more accurate big picture view.

Livingston et al published a review study in 2014 that compiled data from 11 published gastric bypass weight loss studies. Of note, only the studies with the highest quality weight loss data were included. Livingston reported gastric bypass weight loss to be 68% EWL at 2 years after surgery, and 65% EWL at 3-5 years after surgery.*

Livingston also reported the range of average %EWL results between the different studies, which means between the different surgeons/programs. At 2 years after surgery, the range of weight loss outcomes between the different surgeons/programs was reported to be 51-78% EWL. At 3-5 years, the range was reported to be 58-68% EWL.

This variation between the different studies is significant. The difference between 51% EWL and 78% EWL is about 30 pounds for a typical patient who starts out 100 pounds over ideal weight. This review study shows that some gastric bypass surgeons/programs achieve better weight loss outcomes than others.*

Long-Term Gastric Bypass Weight Loss – Published Studies

There have been many fewer published studies on long-term weight loss (10+ years) after gastric bypass, so the data are not as robust as for short-term weight loss (1-5 years). There are sufficient data to draw some conclusions on overall average long-term gastric sleeve weight loss, but not enough to draw conclusions about variation between different surgeons/programs.

Good long-term gastric bypass weight loss studies include Pories et al, Obeid et al, and Higa et al. These 3 studies report average weight loss to be 55-60% EWL at 10 years after gastric bypass, with an overall average of 57% EWL.*

* The weight loss statistics on this page are averages. Individual patients can lose more or less weight than the average.


Ideal Body Weights for Men and Women

Women (height ft./in.) Ideal Weight* (pounds) Men (height ft./in.) Ideal Weight* (pounds)
5’0″ 122
5’1″ 125
5’2″ 128
5’3″ 131
5’4″ 134 5’4″ 143
5’5″ 137 5’5″ 145
5’6″ 140 5’6″ 148
5’7″ 143 5’7″ 151
5’8″ 146 5’8″ 154
5’9″ 149 5’9″ 157
5’10” 152 5’10” 160
5’11” 155 5’11” 164
6’0″ 158 6’0″ 167
6’1″ 171
6’2″ 175
6’3″ 179
6’4″ 183

* Ideal weights above are derived from the Metropolitan Life Insurance Company height/weight tables, 1983, New York, New York. Ideal weights above are the midpoint weights from the medium frame size weight range. Weights include 3-5 pounds of clothes. Heights assume no shoes.

  • 76% excess weight loss 1 year after bypass*
  • 72% excess weight loss 5 years after bypass*
  • 65% excess weight loss 10 years after bypass*

Gastric Bypass before & after

See more
  • Tami
  • Procedure:Gastric Bypass
  • Weight Lost: 75 lbs
  • Excess Weight Lost: 85%
  • Disclaimer: Individual results vary
I had gastric bypass 8 years ago with Dr. Oliak and I would do it again tomorrow. It was the…
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