Researchers studied 824 people in China who had one of two types of weight loss surgery to see which one worked better. One surgery makes your stomach smaller (sleeve gastrectomy), while the other reroutes your digestive system (gastric bypass). Both surgeries helped people lose weight safely, but they worked differently depending on what health problems people had. People with diabetes did better with the bypass surgery, while those with liver problems did better with the sleeve surgery. However, both groups needed to take vitamin supplements afterward because their bodies couldn’t absorb nutrients as well.

The Quick Take

  • What they studied: Whether two different weight loss surgeries (sleeve gastrectomy and gastric bypass) work equally well or if one is better than the other for different types of patients
  • Who participated: 824 obese patients in China who had weight loss surgery between 2014 and 2022. The researchers carefully matched 412 people in each surgery group so they were as similar as possible at the start
  • Key finding: Both surgeries helped people lose weight and improved their health, but gastric bypass worked better for people with diabetes (lowering blood sugar more), while sleeve gastrectomy worked better for people with fatty liver disease
  • What it means for you: If you’re considering weight loss surgery, the type that’s best for you may depend on your specific health conditions. Talk with your doctor about whether you have diabetes, liver problems, or high cholesterol—this might help decide which surgery is right for you. Both surgeries require lifelong vitamin supplements.

The Research Details

This was a retrospective study, meaning researchers looked back at medical records from patients who had already had surgery between 2014 and 2022. They compared two groups of patients who had different weight loss surgeries. To make the comparison fair, they used a special matching technique to ensure the two groups were as similar as possible before surgery—same age, weight, and health conditions. They then tracked how much weight people lost and measured changes in their blood work at 6 months and 12 months after surgery.

The two surgeries studied were: (1) Sleeve gastrectomy, where doctors remove about 75% of the stomach, making it much smaller, and (2) Gastric bypass, where doctors create a small pouch from the stomach and connect it directly to the small intestine, bypassing most of the stomach and part of the intestines. Both are done using minimally invasive laparoscopic techniques with small cuts.

The researchers measured weight loss, blood sugar control, liver health, cholesterol levels, blood pressure, and nutritional status. They also looked at whether factors like alcohol use, gender, and existing health conditions affected the results.

This research matters because weight loss surgery is a major decision with permanent changes to your body. Understanding which surgery works better for different health conditions helps doctors and patients make informed choices. The matching technique used here makes the comparison more reliable because it reduces bias—comparing people who are truly similar except for the type of surgery they had.

This study has several strengths: it included a large number of patients (824), used a rigorous matching method to create fair comparison groups, and followed patients for a full year after surgery. However, it’s a retrospective study, meaning researchers looked at past records rather than randomly assigning people to surgery types, which is less definitive than a randomized trial. The study was conducted in China, so results may not apply equally to other populations. The researchers were careful to measure multiple health markers, not just weight loss.

What the Results Show

Both types of surgery successfully helped patients lose weight and improved their health markers over 12 months. The surgeries were safe, with no major safety concerns reported.

For patients with type 2 diabetes, gastric bypass was significantly more effective. People who had gastric bypass showed much better improvement in their blood sugar control (measured by HbA1c levels) compared to those who had sleeve gastrectomy. This is important because better blood sugar control means better diabetes management.

For patients with fatty liver disease (a condition where fat builds up in the liver), sleeve gastrectomy appeared to work better. Liver enzyme levels improved more in the sleeve gastrectomy group, suggesting the liver was healthier after this surgery.

Women showed different benefits depending on the surgery type. Six months after sleeve gastrectomy, women had lower BMI and blood sugar. Twelve months after gastric bypass, women had lower BMI and blood pressure. This suggests gender may play a role in how well each surgery works.

Alcohol consumption negatively affected outcomes in both groups, with people who drank alcohol showing more weight regain after surgery. This suggests that lifestyle changes, including limiting alcohol, are important for surgery success. Both surgery groups experienced significant vitamin D deficiency after surgery—over 60% of patients in both groups didn’t have enough vitamin D. This is a serious concern because vitamin D is important for bone health and immune function. The study didn’t find major differences in weight loss between the two surgery types overall, but the differences appeared in specific health conditions.

These findings align with previous research showing that gastric bypass is particularly effective for diabetes management because it changes how the body produces hormones that control blood sugar. The finding about vitamin D deficiency matches what other studies have shown—weight loss surgery patients need lifelong vitamin supplementation. The observation that sleeve gastrectomy may be better for liver disease is valuable because it adds to growing evidence that different surgeries have different metabolic effects beyond just weight loss.

This study looked at past medical records rather than randomly assigning people to surgery types, which is less definitive. The study was conducted only in China with Chinese patients, so results may not apply equally to other ethnic groups or countries. The researchers only followed patients for 12 months, so we don’t know about long-term outcomes beyond one year. The study didn’t deeply explore why one surgery worked better for certain conditions. Some patients may have been lost to follow-up, which could affect results. The study didn’t measure all possible nutritional deficiencies, only vitamin D.

The Bottom Line

If you have type 2 diabetes and are considering weight loss surgery, gastric bypass may be more effective for controlling your blood sugar (moderate confidence). If you have fatty liver disease, sleeve gastrectomy may be the better choice (moderate confidence). Both surgeries are safe options for weight loss (high confidence). Regardless of which surgery you choose, you will need to take vitamin supplements for life, especially vitamin D (high confidence). Avoiding alcohol after surgery is important for maintaining weight loss (moderate confidence).

This research is most relevant for people considering weight loss surgery, especially those with type 2 diabetes, fatty liver disease, high cholesterol, or high blood pressure. It’s also important for doctors who recommend weight loss surgery. People who have already had weight loss surgery should pay attention to the vitamin deficiency findings. This research is less directly relevant to people managing weight through diet and exercise alone, though the findings about surgery effectiveness may inform their decisions.

Weight loss and health improvements began showing within 6 months after surgery, with additional improvements by 12 months. However, this study only followed patients for one year, so we don’t know if benefits continue, plateau, or decline after that. Vitamin deficiencies appeared within the first year, so supplementation should start immediately after surgery and continue long-term.

Want to Apply This Research?

  • If you’ve had or are considering weight loss surgery, track your weight weekly and blood sugar levels (if diabetic) every 1-2 weeks. Also monitor your energy levels and any symptoms of nutritional deficiency like fatigue, bone pain, or muscle weakness. Log your vitamin supplement intake daily to ensure compliance.
  • Set a daily reminder to take your vitamin supplements, especially vitamin D, since the study shows most surgery patients become deficient. If you’re considering surgery, use the app to discuss your specific health conditions (diabetes, liver disease, high cholesterol) with your doctor to help decide which surgery type might be best for you. Track alcohol consumption to monitor its impact on your weight loss progress.
  • Create a long-term tracking system that monitors weight trends monthly, blood sugar control quarterly (if diabetic), and vitamin D levels annually. Set alerts for any concerning weight regain patterns. Track lifestyle factors like alcohol use and exercise that affect surgery outcomes. Share this data with your healthcare provider at regular check-ups to ensure you’re getting the support you need.

This research compares two types of weight loss surgery in a Chinese population and should not be used to make personal medical decisions without consulting your healthcare provider. Weight loss surgery is a major procedure with permanent changes to your body and carries risks. The findings about which surgery is better for specific conditions are based on one study and should be discussed with your doctor in the context of your individual health situation. If you have type 2 diabetes, fatty liver disease, or other chronic conditions, work with your medical team to determine if weight loss surgery is appropriate for you and which type might be best. This information is educational only and does not replace professional medical advice.