Some of you may have seen the documentary Fed Up, which tells us “everything we’ve been told about food and exercise for the past 30 years is dead wrong.”

We respectfully disagree.

Before we well you why, here’s the premise of the film in a nutshell: Made by director Stephanie Soechtig, executive producer and narrator Katie Couric, Laurie David and Regina Scully, the film points to our increased sugar consumption as a major cause of skyrocketing obesity rates. The reason for this dramatic increase in sugar (and other refined carbs found in “junk,” fast and processed foods), they say, has to do with fat. Beginning in the late ’70s and early ’80s, saturated fat was implicated in conditions ranging from cancer to heart disease. People wanted to cut fat from their diets, and the market responded. But in order to make foods with little to no fat in them taste palatable, processed food manufacturing companies turned to sugar, resulting in a doubling of Americans’ sugar consumption between 1977 and 2000.

The solution to the obesity epidemic, we’re told, is to jettison refined carbohydrates and cook at home with “whole foods,” meaning whole grains, whole fruits, and whole vegetables.

So here’s why Marcia and I disagree with Fed Up. Although it is obvious that obesity rates have risen steeply over the last 30 years, Marcia’s own clinical experience and a review of the literature doesn’t support the conclusions of Soechtig, Couric, and their assembled team of talking heads. Thirty years ago Americans were much thinner and there were virtually no eating disorders, even though the American diet included refined carbohydrates—in the form of white bread, white sugar, and processed foods—at most meals. To say that obesity rates increased because we are eating more sugar and white flour is like claiming, as one researcher has, that because there is a historical correlation between increased bottled water consumption and obesity, drinking bottled water causes obesity.

The more important difference in our diets between then and now is not the increase in refined carbs, but that meals have taken a back seat to snacks and that both have suffered from “portion creep,” becoming larger and larger over time.

In Marcia’s clinical practice, she advises her overweight patients to move to eating just three meals a day, making sure each meal contains a high-quality protein and some sort of complex carb (white bread, rice, and potatoes are okay, and so are whole grains and legumes), some fat, some veggies, and to save room for dessert. Her patients also learn how to tell what a single portion size should look like (usually between half to a whole cup); a restaurant portion for one in America often is actually enough for two or more. Her patients slowly and permanently lose weight because they are able to stay on this diet without falling back on snacking and bingeing.

Fed Up also makes the case that sugar is an addictive substance. One of the film’s experts, Dr. David Ludwig, tells us that “sugar is eight times more addictive than cocaine,” while another prominent medical figure, Dr. David Kessler, notes that “our brains are constantly being hijacked” by the irresistibly seductive qualities of the junk and processed foods that surround us.

The thing to know is that such research is in its infancy, and there are no evidence-based research findings to back up Drs. Ludwig and Kesssler’s claims. Marcia has noticed that high-sugar foods eaten alone do seem to charge people up and often initiate the urge to binge. On the other hand, high-sugar foods (in other words, dessert) consumed at the end of the meal add to a feeling of satisfaction and well-being and decrease the urge to snack later. This is why with her patients she recommends that high-sugar foods be eaten only at the end of meals and not as snacks. This allows the sugar to be “diluted” by the other nutrients and food components, and its absorption slowed.

Although Drs. Ludwig and Kessler may be right about an addictive element to sugar eaten alone and in between meals, sugar is not like cocaine. We need sugar in our blood stream for our central nervous system to function. Most of us know how bad and impairing low blood sugar feels.

Lest you think that we disagree with everything about Fed Up, there are things to commend the film for, such as the concern we share about the onslaught of processed food advertising aimed at children. We also agree on the need to shift from blaming children, teens, and adults who battle obesity every day to providing them with constructive nutrition counseling.

But the bottom line is that all of Marcia’s patients have tried and failed to stay on the kind of diet Fed Up recommends: a whole foods-only diet that involves reading labels and banning refined carbohydrates and processed foods from their homes. They can do it for a while, but feel deprived and eventually return to overeating, snacking, and bingeing. And while in an ideal world we would all cook at home and eat healthy meals together, that’s not going to happen every day.

Yet we can strive to eat balanced meals and normal portion sizes, whether at McDonald’s or at Grandma’s house, and choose the path of moderation over an obsession with nutrition labels and grams of added sugar. After all, look what happened last time we vilified an age-old element of our diet, saturated fat?