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Since its release in theaters on May 2, the anti-“Big Food” documentary has received plenty of media attention and praise. Through stories and expert commentary, the film, narrated by Katie Couric, strives to bring attention to the underlying causes of youth obesity—and places the blame squarely on added sugars. For this reason, New York Times food writer Mark Bittman  “probably the most important movie to be made since An Inconvenient Truth.”

Given the accolades, it’s hard to imagine detractors, but remarks of disapproval keep coming, including from spokespeople at both the (ASN) and (AND), who focus on the documentary’s one-sided and sugar-obsessed take on obesity. Beyond stigmatizing a nutrient that’s critical to fueling exercise—and has repeatedly been shown to enhance athletic performance—Fed Up falls short on emphasizing the role of other calorie sources in weight gain, and it discounts one of the most powerful tools in the war on obesity: physical activity.

While added sugars are a significant part of the problem because they are widely used to make food appetizing, they are far from the whole problem, says Dr. David Katz, director of Yale University’s and listed as a member of the scientific advisory board for Fed Up. “In terms of overall health outcomes, the evidence overwhelmingly indicates the conjoined importance of what we do with our forks and what we do with our feet,” he says.

If Dr. Katz is straightforward in his criticism, he is joined by many other nutrition experts and organizations who have taken a harder line against the film. Angela Lemond, a registered dietitian nutritionist and AND spokesperson, says that the film’s minimizing of the benefits of exercise is “truly unfortunate” and “irresponsible,” noting that sugar is a quickly absorbed source of carbohydrate that is crucial for exercise performance. Moreover, the film’s focus on sugar as a major factor in contributing to obesity is a “biased view” not shared by the majority of objective scientists, says James O. Hill, a professor of pediatrics and medicine at the University of Colorado, Denver and an ASN spokesperson.

“Research is clear now that adding sugar to a diet and taking away the same number of calories does not cause weight gain or any other of the outcomes attributed to sugar in this film,” Hill says.

But Hill’s chief criticism of the film is the absence of any expert on physical activity. Based on his own research at the , which he founded, an hour or more of physical activity per day is key for long-term weight management success. The registry follows more than 6,000 formerly obese people who have succeeded in keeping weight off permanently. Regardless of how many calories that activity burns, the reason an hour or more of daily exercise works may be due to a change in the body’s biology that helps control appetite and food intake, Hill explains.

While Fed Up blames rising obesity rates on sugar, consumption of added sugars has actually fallen by a quarter over the past decade, with most of the reduction coming from a decline in sugar-sweetened beverages, according to national survey data, says ASN spokesperson Dr. Roger Clemens, chief science officer for specialty ingredient supplier . He also served on the USDA 2010 Dietary Guidelines Advisory Committee. Dr. Clemens says that Fed Up “misconstrues the evidence from many studies and confuses customers” about the role of sugar and processed foods in promoting obesity.

As an avid cyclist who enjoys a regular 50-mile ride, Dr. Clemens stresses the role of sugars in fueling exercise. His own sports drink and exercise fuel of choice: orange juice plus peanut butter and jelly sandwiches. He also says the film doesn’t take into account that exercise will help improve the way sugar is handled in the body through improved insulin sensitivity. Guidelines on sugar intake for active versus nonactive people should not be the same, he says.

While Fed Up has done much to reignite the national debate on obesity and sugar, it’s crucial to separate fact from narrative function. Active people and athletes need sugar to perform. When it comes to obesity, no single nutrient should take all the blame. When it comes to weight loss, a focus on the whole diet is necessary and exercise remains key.

“For health, [exercise is] essential—elemental. The importance cannot be overstated,” says Dr. Katz. “For weight maintenance, also vital; for weight loss per se, diet matters more just because it is so much easier to out-eat exercise than to out-exercise an unregulated intake of calories.”