Does fiber boost weight loss?

fiberfoodsSketchy interpretation of a recent study.

You may have seen the headlines recently “To Lose Weight.. Focus on Fiber“.   This idea is not new.  It’s been around for decades.  So when I saw the recent headlines, I thought the study behind them must be pretty extraordinary to generate so much buzz.  After reading the study, I was pretty underwhelmed.

The researchers weren’t actually evaluating the benefits of fiber.  That was assumed.  They were comparing a relatively simple diet plan (“Eat more fiber”) to the more complex rules of the American Heart Association diet, with its list of food dos and don’ts.  The study subjects were obese, and at risk of developing Type 2 diabetes.  They were divided into 2 diet groups, and followed the diet for a year:

  1. The typical AHA diet, with a list of 13 rules such as choosing lean meats, eating more fish, eating more fiber-rich foods, limiting sodium and limiting sugar.
  2. A diet with a minimum of 30 grams of fiber from food (not supplements) every day.

At the end of the year, both groups had lost weight.  The AHA group had lost slightly more weight.  Everyone saw improvements in blood pressure and insulin resistance.  But even though the AHA subjects lost slightly more weight, the researchers declared victory for the high fiber diet.  Why?

Here’s why: they felt that keeping diet rules simple made it easier for people to stick to a plan.  The advice to “eat at least 30 grams of fiber a day” resulted in lots of beneficial changes in food choices, by default.  High fiber foods are vegetables, whole grains, legumes, nuts and fruit, all foods people should eat more of.  And also by default, if someone is packing their diet with high fiber foods, there’s less room for low fiber junk, like chips, sweets and soft drinks.  Added benefit: high fiber foods are filling, so there’s less room in your stomach if you eat plenty of those.  Result: lower calorie intake and weight loss.

Keep in mind, these subjects were on this diet for a year, and they only lost 4-6 lbs on average.  That’s not much, considering these subjects were obese and probably could have lost 30 or more pounds.  But they didn’t necessarily cut down on food intake or have to deal with hunger and the deprived feeling of “being on a diet”.  They could eat delicious food and feel satisfied, but still lose some weight and improve health risk factors.  Not a bad outcome.

So let’s review: Why more fiber?

  • It’s filling, so you don’t have room for high calorie junk
  • You aren’t constantly hungry.
  • Foods that are naturally high fiber are extremely nutrient-dense, so you get lot of vitamins, minerals and antioxidants with the fiber.
  • Fiber itself has beneficial effects on your digestion, aside from weight loss.
  • You might lose some weight without even ‘dieting’.

Conclusion: even without calorie restriction, a high fiber diet can boost a weight loss.  But it’s not a magic potion.  Loading up on fiber won’t fix a junky diet and won’t cause pounds to melt off.  And fiber supplements aren’t a substitute for high fiber foods.

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