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DOUBLE the rate of anemia after weight-loss surgery

Weight-loss surgery increases patients’ risk of dangerous anemia two-fold, according to a new observational study. 

Researchers at Stanford University analyzed a group of people, with an average age of 51, who underwent a Roux-en-Y gastric bypass to treat obesity. 

At the start of the study, before operating, 20 percent of them had the red blood cell deficiency. At their 10-year follow-up, that rate more than doubled to 47 percent. 

Rates were particularly high among those who had not scheduled a check-up, but merely responded to a spontaneous phone interview. 

The researchers warn the study, published today by JAMA, shows patients need to be more conscious about the need to take nutritional supplements as their digestive system changes after surgery. 

At the start of the study by Stanford University, 22 percent of the patients had red blood cell deficiency before operating. At the 10-year follow-up, the rate rose to 57 percent


The three most common weight loss surgeries are lap band, gastric sleeve and gastric bypass operations. 


A lap band procedure is an inflatable band placed around the top of the stomach, restricting food intake. 

The average cost is $14,500 and patients lose around 10 percent of their original body weight. 

Pictured: An illustration of lap band surgery

Pictured: An illustration of lap band surgery


The gastric sleeve is a non-reversible procedure and involves removing 80 percent of the stomach. 

It stabilize gut hormones which are off-balance in obese people, driving them to crave food when they don’t need it.

The average cost is $15,000 and patents lose around 17 percent of body weight.  


Gastric bypasses divides the stomach into a small upper pouch and a much larger pouch. 

The surgeon rearranges the small intestine to connect to the small pouches.

The average cost is $23,000 and patients lose around 27 percent  of body weight.  

While anemia can be mild, it can cause dizziness, light-headedness, weakness, and heart palpitations, as well as brittle nails and headaches. 

It can lead to iron and b-12 deficiencies, and affects the movement of oxygen to your lungs.  

‘Our study suggests that follow-up with bariatric specialists more than five years after surgery, rather than with specialists with no bariatric expertise, can decrease long-term anemia risk,’ said lead author Dr Dan Eisenberg of the veteran affairs department at the university. 

‘This finding may demonstrate the bariatric specialist’s specific understanding of the long-term risk for nutritional deficiency after RYGB and the importance of vitamin and mineral supplementation.’

The study included 74 patients, 78 percent of whom were men, after weight-loss surgery at a single Veterans Affairs Medical Center.

The average rate of preoperative anemia was 20 percent; the rate increased 10 years after Roux-en-Y to 47 percent.

At 10 years after surgery, the anemia rate in the group without bariatric specialist follow-up increased to 57 percent, from 22 percent before surgery. 

The rate of anemia in the group with bariatric specialist follow-up did not increase significantly after 10 years (up to 19 percent from 13 percent).

Experts suggest this could show that those without a specialist were less aware of the nutritional changes they would suffer.  

The major limitation of this study was the size of the group with bariatric specialist follow-up, which may be too small to identify a significant difference in the 10-year anemia rates compared with preoperative rates.

However, the researchers insist it is a red flag that we need to further explore how weight-loss surgery impacts the blood system, as rates of obese patients going under the knife sky-rocket. 

Meanwhile, more and more research has emerged showing that, while risky, the operation has some unexpected added benefits. 

For example, decades of studies have shown weight loss surgery staves of patients’ hunger pangs by rebalancing their hormones. 

More recently, a study by the Medical University of Vienna found the damage done to the cells by weight gain can be reversed by bariatric surgery.

Obese people are prematurely old, with eroded cells and inflamed fat tissue.

But researchers found gastric bypass operations could not only stop the effects – but reverse them. 

Another study found weight-loss surgery – including gastric bands – helps to ‘re-wire’ the brain, leaving people less interested in food.

The study, carried out at the University of Missouri-Kansas City, compared those who lost weight after bariatric surgery, and those who opted for more conventional dieting methods.

Following their weight loss, when confronted with images of pizza and other appetising food, scientists noticed the brains of the dieters were more active in the medical prefrontal cortex – the part of the brain known to regulate emotion and evaluate how we feel.

However, there are clear downsides. 

Beyond suggestions of an increased anemia risk, other studies have shown weight loss surgery can leave patients with life-long gastrointestinal problems and food intolerance.

Recently, researchers in the Netherlands examined data on 249 extremely obese patients who had what’s known as laparoscopic Roux-en-Y gastric bypass, which reduces the stomach to a small pouch about the size of an egg.

Two years after surgery, these patients had lost about 31 percent of their total body weight on average.

But compared to the control group of 295 obese people who didn’t have operations, the gastric bypass patients were far more likely to experience indigestion and an inability to tolerate multiple foods.