Clinical Research
Sleeve gastrectomy or mini gastric bypass? Real numbers from 92 patients with super obesity.
Choosing between sleeve gastrectomy or mini gastric bypass is one of the most common questions we hear in clinic, and it matters even more when the body mass index (BMI) is 50 or higher. Because this decision should rest on evidence, this article summarizes a clinical study published in 2025 in the Journal of Gastrointestinal Surgery, co-authored by Dr. Ahmed Shinkar, that compared both operations for weight loss and nutritional deficiencies over a full year.
💡 Key Takeaways
- The study included 92 patients with super obesity: 53 had a sleeve and 39 had a mini gastric bypass (OAGB).
- Weight loss was similar for the first 6 months, then the mini bypass pulled ahead at 12 months.
- Iron, vitamin B12, zinc and protein deficiencies were more common after the mini bypass.
- The right choice depends on age, other illnesses and the ability to commit to follow-up.
About the Study: Who Were the Patients?
This was a retrospective study of patients who had bariatric surgery between January 2022 and December 2023 at Al-Zahraa University Hospital in Cairo. The average weight before surgery was about 156 kg and the average BMI was around 57, so every patient fell into the super obesity category.
However, the mini bypass group was older (median age 41 vs 33 years) and had more conditions such as diabetes, high blood pressure and heart disease. The results should be read with this difference in mind.
92 Patients
53 in the sleeve group and 39 in the mini gastric bypass group.
BMI Around 57
The average weight before surgery was about 156 kg in both groups.
12 Months of Follow-up
Weight was measured at 3, 6 and 12 months, with blood tests before surgery and after one year.
Weight Loss After Sleeve Gastrectomy or Mini Gastric Bypass
At 3 and 6 months, there was no meaningful difference between the two operations. By the end of the first year, though, a clear advantage appeared for the mini gastric bypass, as the table below shows.
| Measure at 12 months | Sleeve gastrectomy | Mini gastric bypass |
|---|---|---|
| Median weight | 89 kg | 78.5 kg |
| BMI | 32.4 | 29.7 |
| Excess weight loss | 78.2% | 86.6% |
| Total body weight loss | 43.3% | 50.4% |
In other words, both groups did very well, losing well over half of their excess weight. Still, the mini bypass reached a lower weight by the one-year mark. Learn more about expected weight loss after mini gastric bypass.
Sleeve vs Mini Gastric Bypass: Operating Time and Complications
The sleeve was clearly faster, with a median of 30 minutes compared with 53 minutes for the mini bypass. This makes sense, because the bypass adds a step to connect the intestine.
Hospital stay was almost identical: about 98% of patients in both groups went home after just one day. Complication rates were low in both groups (3.8% for the sleeve and 7.8% for the bypass), with no statistically significant difference.
The more serious complications occurred in the bypass group, which was older and had more heart disease and diabetes. Part of this may reflect the patients’ health rather than the operation itself.
Vitamin Deficiencies After Sleeve Gastrectomy or Mini Gastric Bypass
This is the other side of the comparison. After one year, several levels were clearly lower in mini bypass patients, even though everyone followed the same supplement program.
- Iron: median 30.6 after the bypass vs 65.8 after the sleeve.
- Iron stores (ferritin): 28.3 vs 45.7.
- Vitamin B12: 289.5 vs 567.
- Hemoglobin: 10.2 vs 11.6.
- Albumin (protein): 3.3 vs 4.0.
- Zinc: 53.4 vs 64.3.
The reason is that the mini bypass partly works by reducing absorption: food skips a section of intestine that absorbs iron and other nutrients. That is why supplements after mini gastric bypass are a lifelong commitment.
How to Choose a Sleeve or Mini Gastric Bypass
- Age and other illnessesA sleeve may be a safer first step for older patients or those with heart problems, with the option to convert later if needed.
- Risk of malnutritionPatients with anemia or who find it hard to take supplements regularly may do better with a sleeve.
- Weight-loss goalWhen more weight loss is needed, or with type 2 diabetes, the mini bypass may be the better option.
- RefluxSevere reflux before surgery affects the choice and should be discussed in detail with your surgeon.
Also read about the difference between mini and Roux-en-Y gastric bypass for the full picture of bypass options.
You can read the full study in the Journal of Gastrointestinal Surgery for more scientific detail.
FAQs About Sleeve Gastrectomy or Mini Gastric Bypass
Which is better for super obesity: sleeve or mini gastric bypass?
There is no single answer for everyone. In the study, the mini bypass produced more weight loss at one year, while the sleeve caused fewer vitamin and mineral deficiencies. The decision depends on age, other illnesses and the ability to commit to follow-up.
Are sleeve results weak in patients with super obesity?
No. Sleeve patients in the study lost about 78% of their excess weight within a year, which is an excellent result. The mini bypass simply reached a slightly higher figure.
Can a mini gastric bypass be done after a sleeve?
Yes. Conversion is possible later if weight loss is not enough or weight returns, which can be a sensible plan for older or higher-risk patients.
Do mini gastric bypass patients need vitamins for life?
Yes. Because absorption is reduced, patients need daily supplements and regular blood tests for life to prevent iron, vitamin B12, zinc and protein deficiencies.
Unsure Between a Sleeve or Mini Gastric Bypass?
Book a consultation with Dr. Ahmed Shinkar to assess your case and choose the right operation for you.
Book Your ConsultationDisclaimer: This article is for educational purposes only and does not replace a consultation with a qualified physician.