“Fed Up” is structured around interviews with obese adolescents and their families. (RADIUS-TWC)

The latest in a line of documentaries critiquing the American diet, “Fed Up” quickly zeroes in on what would appear to be its villain. According to the film, added sugar, in all forms — including not just the demonized high-fructose corn syrup, but also more natural-sounding throwbacks such as “pure” cane sugar — is almost single-handedly responsible for what one interview subject calls the obesity tsunami sweeping the nation, as well as the sharp rise in diabetes.

Of course, the increased sugar in processed foods is just the weapon that’s killing us, according to director Stephanie Soechtig and journalist Katie Couric, who narrates and produced the informative and at times anger-inducing film. The real culprit, “Fed Up” argues, is an industry pushing sugar-laden junk food on an unsuspecting public.

One particularly telling commentary — and a source of grim, if unintended, humor — comes from a mother struggling to help her obese teenager find more healthful meal options. (The movie is structured around interviews with several morbidly obese adolescents and their families.) Recently, Mom tells us, she switched from buying Hot Pockets to buying “lean” Hot Pockets. Though meant sincerely, the line deserves to be met with a derisive snort.

There’s a reason federally mandated nutrition labels list the “daily value” percentage for everything in that Hot Pocket — fat, sodium, carbs, protein, etc. — except sugar. That’s because even foods that are labeled dietetic typically contain more sugar than the Food and Drug Administration considers healthy. When you take the fat out of food, there goes the flavor, too. You’ve got to give people another reason to crave it.

What this suggests is that the real problem isn’t sugar, but sugar education. If consumers only knew that the stuff is not just addictive, but poisonous — one of the film’s experts calls it a “chronic, dose- dependent” liver toxin — they might make better choices at the checkout counter. Unfortunately, “Fed Up” doesn’t seem to recognize the problem of food deserts, which can hamstring even the best-intentioned efforts to teach people how to eat right.

(For an exposé of the food desert phenomenon, in which many communities simply don’t have options other than buying processed foods, I strongly recommend the 2012 documentary “A Place at the Table.”)

Celebrities appearing in “Fed Up” include former president Bill Clinton and former FDA commissioner David A. Kessler, both of whom bemoan the lack of government foresight on obesity and diabetes. (Opponents of so-called nanny state efforts to regulate, say, soft drink size are given short shrift.) But it’s author-activist Michael Pollan who delivers the film’s most succinct message when he says that the single best way to improve one’s diet is simply to cook what you eat. And no, that doesn’t mean microwaving a Hot Pocket.

Making dinner from scratch can be a challenge for people pressed for time, inspiration and cash. Subsidies propping up the fast-food and processed-food industries often make it cheaper and more convenient to buy prepared foods than wholesome ingredients. Change, according to the film, isn’t going to happen unless it comes in the form of a revolution.

For that reason, “Fed Up” isn’t so much a warning to the ignorant shopper or a tip for the unimaginative chef as it is a rallying cry. It succeeds in firing up the choir. Whether it will convert the complacent is an open question.

★ ★ ★

PG. At Landmark’s E Street Cinema. Contains thematic elements including smoking images, and brief mild language. 99 minutes.