Bariatric Surgery vs. Diet

Let’s say you’re trying to lose 20 pounds – or boost your immunity – or increase your ability to fight Covid – or even cancer. Well – the amazing thing is – with the right diet – you are well on your way to achieving these vital health goals. Welcome to the NutritionFacts podcast. I’m your host Dr. Michael Greger. 

Today, we look at how losing weight without rearranging your gastrointestinal anatomy carries advantages beyond just the lack of surgical risk.

The surgical community objects to the characterization of bariatric surgery as merely internal jaw wiring, cutting into healthy organs just to discipline people’s behavior. They’ve gone as far as to rename it “metabolic surgery,” suggesting the anatomical rearrangements cause changes in digestive hormones that offer unique physiological benefits. As evidence, they point to the remarkable remission rates for type 2 diabetes.

After bariatric surgery, about 50 percent of obese diabetics and 75 percent of super-obese diabetics go into remission, meaning they have normal blood sugars on a regular diet off all diabetes medications. The normalization in blood sugars can happen within literally days after the surgery. And then fifteen years after the surgery, 30 percent may remain free from their diabetes (compared to a 7 percent cure rate in a nonsurgical control group). Are we sure it was the surgery, though?

One of the most challenging parts of bariatric surgery is lifting the liver. Since obese individuals tend to have such large fatty livers, this can be tricky, risking liver injury and bleeding. Enlarged livers are one of the most common reasons less invasive laparoscopic surgery turns into to fully invasive open surgery, leaving the patient with a large full-belly scar, and increased risk of wound infections, complications, and recovery time. But lose even just 5 percent of your body weight, and your fatty liver may shrink by 10 percent. That’s why those awaiting bariatric surgery are put on a diet. Then, after surgery, patients are typically placed on an extremely low-calorie liquid diet for weeks. Could their improvement in blood sugars just be from the calorie restriction, rather than some sort of surgical metabolic magic? Researchers decided to put it to the test.

At a bariatric surgery clinic at the University of Texas, patients with type 2 diabetes scheduled for a gastric bypass volunteered to first undergo an identical period of calorie restriction, but without the surgery. They were placed in the hospital and put on the same diet they would be on immediately before and after the surgery for ten days, averaging less than 500 calories a day to mimic the surgical situation. Then, the researchers waited a few months so the patients would gain the weight back and, then put them through the actual surgery, matched day-for-day to the diets they were on before. So, the same patients and the same diets, just with or without the actual surgery.

If there was some sort of metabolic benefit to the anatomical rearrangement, they would have done better after the actual surgery, but in some ways they actually did worse. The calorie restriction alone resulted in similar improvements in blood sugar, pancreatic function, and insulin sensitivity, but several measures of diabetic control improved significantly more without the surgery. So, the surgery seemed to put them at a metabolic disadvantage.

The calorie restriction works by first mobilizing fat out of the liver. Type 2 diabetes is thought to be caused by fat building up in the liver, and then spilling over into the pancreas. Everyone may have a “personal fat threshold” for the safe storage of excess fat. When that limit is exceeded, fat gets deposited in the liver, where it causes insulin resistance. The liver attempts to offload some of the fat (in the form of a fat transport molecule called VLDL), which then gets stuck in the pancreas, and can kill off the cells that produce insulin. By the time diabetes is diagnosed, half of our insulin-producing cells may have been destroyed. Put people on a low-calorie diet, though, and this entire process can be reversed.

A large enough negative calorie balance can cause a profound drop in liver fat sufficient to resurrect liver insulin sensitivity within seven days. Keep it up, and the liver stops spitting out fat enough to help normalize pancreatic fat levels and function within just eight weeks. Once you drop below your personal fat threshold, you should then be able to resume normal intake and still keep your diabetes at bay. The bottom line is that type 2 diabetes is reversible with weight loss, if you catch it early enough.

Lose more than 30 pounds, and nearly 90 percent of those who have had type 2 diabetes for less than four years can achieve remission, whereas it may only be reversible in 50 percent of whose who’ve lived with the disease for longer than eight years. That’s losing weight with diet alone, though. The remission numbers for diabetics losing even more than twice as much weight with bariatric surgery may only be around 75 percent up to eight years and 40 percent after that.

Losing weight without resorting to surgery may offer other benefits as well. Diabetics losing weight with diet alone can significantly improve markers of systemic inflammation, such as tumor necrosis factor, whereas levels significantly worsened when about the same amount of weight was lost from a gastric bypass.

What about diabetic complications? One of the reasons we don’t want diabetes is that we don’t want to go blind, and we don’t want to have to go on dialysis. Reversing diabetes with bariatric surgery can improve kidney function but, surprisingly, it may not prevent the appearance or progression of diabetic vision loss. Perhaps because bariatric surgery affects diet quantity, but not necessarily diet quality.

This reminds me of a famous study published in the New England Journal of Medicine that randomized thousands of diabetics to an intensive lifestyle program that focused on weight loss. Ten years in, the study was stopped prematurely because the diabetics weren’t living any longer or having any fewer heart attacks. This may be because they remained on the same heart-clogging diet, but just in smaller portions.

In our next story, we look at how weight regain after bariatric surgery can have devastating psychological effects.

How sustainable is the weight loss from bariatric surgery? Most gastric bypass patients end up regaining some of the fat they lose over the first year or two after surgery, but five years later, three-quarters maintain at least a 20 percent weight loss. The typical trajectory for someone who starts out obese at 285 pounds, for example, would be to drop to an overweight 178 pounds two years after bariatric surgery, but then regain back up to an obese 207 pounds. This has been chalked up to “grazing” behavior, where compulsive eaters may shift from bingeing, which becomes more difficult post-surgery, to eating smaller amounts constantly throughout the day. Eight years out, about half of gastric bypass patients continue to describe episodes of disordered eating. As one pediatric obesity specialist described, “I have seen many patients who put chocolate bars into a blender with some cream, just to pass technically installed obstacles [like a gastric band].”

Bariatric surgery advertising is filled with happily-ever-after fairytale narratives of cherry-picked outcomes offering, as one ad analysis put it, “the full Cinderella-romance happy ending.” This may contribute to the finding that patients often overestimate the amount of weight they’ll lose with the procedure, and underestimate the difficulty of the recovery process. Surgery forces profound changes in eating habits, requiring slow, thoroughly-chewed, small bites. Your stomach goes from the volume of two softballs to down to the size of half a tennis ball in stomach stapling, and half of a ping-pong ball in the case of gastric bypass or banding.

As you can imagine, weight regain after surgery can have devastating psychological effects, as patients may feel they failed their last resort. This may explain why bariatric surgery patients are at a high risk of depression and suicide.

Now, severe obesity alone may increase risk of suicidal depression, but even at the same weight, those going through surgery appear to be at higher risk. At the same BMI, age, and gender, bariatric surgery recipients have nearly four times the odds of suicide compared with counterparts not undergoing the procedure. Most convincingly, before-and-after mirror-image analyses show the risk of serious self-harm increases post-surgery among the same individuals.

About 1 in 50 bariatric surgery patients end up killing themselves, or being hospitalized for self-harm or attempted suicide. And this only includes confirmed suicides, excluding masked attempts such as overdoses of “undetermined intention.” Bariatric surgery patients also have an elevated risk of accidental death, though some of this may be due to changes in alcohol metabolism. Give gastric bypass folks two shots of vodka, and because of their altered anatomy, their blood alcohol level shoots past the legal driving limit within minutes. It’s unclear whether this plays a role in the 25 percent increase in prevalence of alcohol problems noted during the second postoperative year.

Even those who successfully lose their excess weight and keep it off appear to have a hard time coping. Ten years out, though physical health-related quality-of-life improves, general mental health tends to significantly deteriorate, compared to pre-surgical levels even among the biggest losers. Ironically, there’s a common notion that bariatric surgery is for “cheaters” who take the easy way out by choosing the “low-effort” method of weight loss.

Shedding the pounds may not shed the stigma of even prior obesity. Studies suggest that in the eyes of others, knowing someone was fat in the past leads them to always be treated more like a fat person. And there’s a strong anti-surgery bias on top of that, such that those who choose the scalpel to lose weight are rated most negatively (for example, being considered less physically attractive). One can imagine how remaining a target of prejudice even after joining the “in-group” could potentially undercut psychological well-being.

There can also be unexpected physical consequences of massive weight loss, like large hanging flaps of excess skin. Beyond being heavy and uncomfortable, and interfering with movement, the skin flaps can result in itching, irritation, dermatitis, and skin infections. Getting a panniculectomy (removing the abdominal “apron” of hanging skin) can be expensive, and has a complication rate exceeding 50 percent, with dehiscence (rupturing of the surgical wound) being the most common complication.

“Even if surgery proves sustainably effective,” wrote the founding director of Yale University’s Prevention Research Center, “the need to rely on the rearrangement of our natural gastrointestinal anatomy as an alternative to better use of feet and forks [(diet and exercise)] seems a societal travesty.”

In the Middle Ages, starving peasants dreamed of gastronomic utopias where food just rained down from the sky. The English called it the Kingdom of Cockaigne. Little could medieval fabulists predict that many of their descendants would not only take permanent residence there, but cut out parts of their stomachs and intestines to combat the abundance. Critics have pointed out the irony of surgically altering healthy organs to make them dysfunctional—mal-absorptive—on purpose, especially when it comes to operating on children. Bariatric surgery for kids and teens has become widespread, and is being performed on children as young as five years old. Surgeons defend the practice by arguing that growing up fat can leave emotional scars and “lifelong social retardation.”

Promoters of preventive medicine argue that bariatric surgery is the proverbial “ambulance at the bottom of the cliff.” In response, proponents of pediatric bariatric surgery have written: “It is often pointed out that we should focus on prevention. Of course, I agree. However, if someone is drowning, I don’t tell them, ‘You should learn how to swim’; no, I rescue them.”

A strong case can be made that the benefits of bariatric surgery far outweigh the risks if the alternative is remaining morbidly obese, which is estimated to shave up to a dozen or more years off of one’s life. Although there haven’t been any data from randomized trials to back it up yet, compared to non-operated obese individuals, those getting bariatric surgery would be expected to live significantly longer on average. No wonder surgeons consistently frame the elective surgery as a life-or-death necessity.

This is a false dichotomy, though. The benefits only outweigh the risks if there are no other alternatives. Might there be a way to lose weight healthfully without resorting to the operating table? That’s what my book How Not to Diet is all about.

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