When people have weight loss surgery and it doesn’t work as well as hoped, doctors sometimes perform a second surgery to fix it. However, new research shows that even after these second surgeries, patients often develop serious nutritional problems. Scientists reviewed 14 studies involving over 1,000 patients and found that vitamin D, vitamin B12, iron, and protein deficiencies remain very common—even when patients take supplements. The findings suggest that people who have had these surgeries need closer monitoring and better supplement plans tailored to their specific situation.

The Quick Take

  • What they studied: Whether people who have a second weight loss surgery (after their first one didn’t work well enough) develop nutritional deficiencies, and which nutrients are most affected.
  • Who participated: 1,049 patients across 14 different studies who had undergone a second weight loss surgery following an initial sleeve gastrectomy (a common type of weight loss surgery where part of the stomach is removed).
  • Key finding: Nutritional deficiencies are very common after revision surgery, with vitamin D, vitamin B12, iron, and protein problems occurring frequently. Iron deficiency showed the biggest differences between different types of revision surgeries (p = 0.025), with some procedures carrying higher risk than others.
  • What it means for you: If you’ve had or are considering a second weight loss surgery, you should expect to need careful nutritional monitoring and personalized supplement plans. Standard supplement regimens may not be enough, and your doctor should regularly check your nutrient levels rather than assuming supplements are working.

The Research Details

Researchers conducted a systematic review and meta-analysis, which means they searched multiple medical databases (PubMed, Scopus, Web of Science, and Cochrane Library) for all published studies about nutritional problems after revision weight loss surgery. They followed strict guidelines called PRISMA to ensure their review was thorough and unbiased. They included 14 studies published through April 2025 that reported specific information about nutrient levels in patients who had undergone revision bariatric surgery after initial sleeve gastrectomy.

The researchers extracted detailed information about specific nutrients: vitamin D, vitamin B12, iron, calcium, albumin (a protein), and anemia (low red blood cells). They then combined the data from all studies using statistical methods to identify patterns and compare outcomes between different types of revision surgeries. They also performed a special analysis to make sure they weren’t counting the same patients twice if they appeared in multiple studies.

This research approach is important because individual studies on this topic often include small numbers of patients, making it hard to draw firm conclusions. By combining data from 14 studies with over 1,000 total patients, the researchers could identify reliable patterns about which nutrients are most problematic and whether certain surgical techniques carry higher risks. This larger combined view gives doctors and patients much better information for making decisions and planning care.

This is a well-designed systematic review that followed international guidelines (PRISMA) for conducting such research. The researchers searched multiple databases to find studies, which reduces the chance of missing important research. They also checked for overlapping patient populations to avoid counting the same people multiple times. However, the quality depends partly on the individual studies included—if those studies had limitations, those limitations carry forward into this analysis. The findings show consistent patterns across studies, which increases confidence in the results.

What the Results Show

The analysis revealed that nutritional deficiencies are extremely common after revision weight loss surgery, even though patients typically take vitamin and mineral supplements. Vitamin D deficiency was particularly frequent in certain types of revision surgeries. Iron deficiency showed statistically significant differences between different surgical approaches, with one type of revision surgery associated with notably higher risk of iron problems.

Albumin levels (which reflect protein status) and anemia rates did not differ significantly between the different types of revision surgeries studied, but anemia remained a common problem overall, affecting many patients regardless of which revision procedure they had. This suggests that protein and red blood cell problems are widespread issues after revision surgery rather than being specific to one surgical technique.

The research highlighted considerable variability in outcomes depending on which revision surgery technique was used, indicating that some procedures may carry higher nutritional risks than others. Despite the routine use of standard supplement regimens, deficiencies in vitamin D, vitamin B12, iron, and protein continued to be frequently reported across all revision types.

Calcium and zinc deficiencies were also reported across revision procedures, though the analysis provided less detailed information about these nutrients compared to vitamin D and iron. The finding that standard supplementation regimens were not preventing these deficiencies suggests that one-size-fits-all supplement plans may be inadequate for this population. The variability between surgical techniques indicates that the specific anatomical changes created by different revision procedures affect nutrient absorption differently.

Previous research has shown that even the initial sleeve gastrectomy surgery can cause nutritional deficiencies, but this study specifically examines what happens when patients need a second surgery. The findings confirm that revision surgery adds additional nutritional challenges on top of those already present from the first surgery. This research extends our understanding by showing that the problem is not just about having surgery once, but that additional surgical procedures compound the nutritional risks.

The study included only 14 research papers, which is a relatively small number for a meta-analysis. The quality and design of these individual studies varied, which could affect the overall conclusions. Different studies measured nutrients at different time points after surgery, making it harder to compare results directly. The research did not provide detailed information about how well patients followed their supplement regimens, which could influence whether deficiencies developed. Additionally, the studies came from different countries and healthcare systems, so results may not apply equally to all populations.

The Bottom Line

If you have had or are planning revision weight loss surgery after sleeve gastrectomy, work closely with your surgical team and a nutrition specialist to develop a personalized supplement plan rather than relying on standard regimens. Get regular blood tests to check your vitamin D, vitamin B12, iron, and protein levels—don’t assume supplements are working without verification. Consider more frequent monitoring in the first year after revision surgery when deficiencies are most likely to develop. These recommendations are based on strong evidence from multiple studies (high confidence level).

This research is most relevant for people who have had sleeve gastrectomy and are experiencing weight regain or inadequate weight loss and considering revision surgery. It’s also important for bariatric surgeons and nutrition specialists who care for these patients. People who have already had revision surgery should pay special attention to these findings. This research is less directly applicable to people who have had other types of weight loss surgery or who are satisfied with their initial sleeve gastrectomy results.

Nutritional deficiencies typically develop gradually over months following revision surgery. Some deficiencies may appear within 3-6 months, while others may take 6-12 months to develop. This is why ongoing monitoring is important rather than assuming you’re fine after the initial recovery period. Benefits from improved supplementation and monitoring may take several months to show up in blood tests and symptom improvement.

Want to Apply This Research?

  • Track your supplement intake daily (vitamin D, B12, iron, calcium, zinc, and protein) and log any symptoms like fatigue, weakness, or hair loss that might indicate deficiencies. Record the dates and results of your blood tests to monitor trends in your nutrient levels over time.
  • Set daily reminders to take your personalized supplement regimen at the same time each day. Schedule quarterly blood work appointments in your calendar to check nutrient levels. Use the app to track which supplements you’re taking and at what doses, and share this information with your doctor at each visit.
  • Create a long-term tracking dashboard that shows your nutrient levels over time (vitamin D, B12, iron, albumin, calcium). Set alerts if you miss supplement doses or upcoming blood test appointments. Monitor and log energy levels, hair quality, and other symptoms that correlate with nutritional status to catch problems early.

This research summary is for educational purposes only and should not replace professional medical advice. If you have had or are considering weight loss surgery, consult with your bariatric surgeon and a registered dietitian nutritionist who specializes in bariatric surgery. The findings presented here apply to revision surgery after sleeve gastrectomy specifically and may not apply to other surgical procedures. Individual nutritional needs vary significantly, and personalized assessment is essential. Always have blood work performed and interpreted by qualified healthcare providers before making changes to your supplement regimen.