For half of March, I engaged in a new ritual before each meal. I’d flip open a cell phone, turn on its camera, and discreetly snap a picture. Then I’d e-mail it to a stranger.

I was testing a new dieting service called MyFoodPhone, which uses camera phones to document subscribers’ intake, then e-mail the results to dietitians for analysis and advice. This service aims to avoid the hassle of jotting down what you ate, then conveying those records to a dietitian later on.

But my first thoughts weren’t about saving paperwork, they were about my fear of getting caught. I worried that somebody would notice my clandestine culinary photojournalism, with the inevitably incredulous reaction, “Did you just take a picture of your food?”

I need not have worried. Once I turned off the camera-shutter sound effect on the Sprint phone that MyFoodPhone loaned for the test, my picture-taking looked like any other form of wireless rudeness. As far as anybody could tell, I was just reading text messages or looking up baseball scores at the dinner table.

MyFoodPhone subscribers begin by answering a questionnaire at the Web site of the Quebec City-based firm,www.myfoodphone.com, which includes both questions anyone could answer (weight, height, exercise habits) and others that assume you’ve had a recent physical exam (cholesterol and glucose levels).

The system then assigns the subscriber a dietitian, who will look at each photo and offer comments on a personalized page at the company’s Web site on the nutritional value of the food as well as advice on improving overall diet.

Sending each picture was surprisingly simple: Select a photo, then send it to one of several of saved addresses: “ABreakfast,” “ALunch,” “AQuestion,” “ASnacks,” and “ASupper.” (“ADessert” and “ADrink” seem major omissions.)

The biggest challenge in documenting my dining turned out to be taking photos that could be deciphered later on. The initial batch of comments from my dietitian exhibited a fair amount of confusion – a cup of tea drew the comment, “Is this tomato soup?”

You can add a voice memo or type out a brief description using the phone’s keypad, but I usually avoided that extra effort and got on with eating.

Most of my digital photos, however, were readable, if sometimes amazingly unappetizing. (Here’s a tip: Photograph a burrito before you’ve wolfed down half of it.)

The dietitian’s comments, posted a day or two after I had uploaded photos, were brief but useful, and often surprising. I found out that my wife’s breakfast cereal was healthier than I’d thought (“Good fiber in the frosted miniwheats”), but the croissant I had on another day got a thumbs-down (“A whole wheat bagel or 2 slices of whole wheat toast would be a great alternative with less fat and more fiber”).

I expected to be scolded for a steak dinner at a reception and an enormous slice of pizza at one lunch, but each got a reasoned thumbs-up: “Excellent portion of red meat” and “Cheese pizza is one of the better options for pizza.”

On the other hand, my typical lunch – a sandwich I’ll bring from home and a can of soda

– was criticized for the sugar content in the beverage. My dietitian offered a simple suggestion, so obvious that I’d never thought of it before: Drink water instead.

The biggest weakness of this system was having to photograph every single meal. Some meals just defy photographic record-keeping. Capturing my food intake at a tapas place was a minor ordeal, and I didn’t even try to photograph the samples I tasted at a cooking demonstration. I could log on to the site and type in descriptions of what I hadn’t shot.

After the first week or so of use, my dietitian supplemented her comments with assessments of whether I was eating too much or too little in six categories, displayed in simple dial graphics. The verdict: too much fat, bread, cereal, rice, and pasta; not enough milk, yogurt, cheese, and fruit. A “Goals” heading offered such general recommendations as “Try to limit your soda intake to 1-2 per week” and “fruit is a great dessert!”

After two weeks, I’d actually made some changes to my diet, somewhat to my surprise: As suggested, I started having water and fruit with lunch and realized that I didn’t actually miss the usual dose of fizzy sugared water.

Perhaps more important, knowing that what I put on my plate would be scrutinized by somebody else had exerted its own deterrent effect. The camera may lie, but not as much as people can.

And that’s the point of such a service, said Lona Sandon, an assistant professor at the University of Texas Southwestern Medical Center in Dallas.

“People also tend to greatly underestimate their portion sizes when writing things down and may intentionally or unintentionally forget to report that chocolate chip cookie in the middle of the day,” Ms. Sandon (also a spokeswoman for the American Dietetic Association) wrote in an e-mail. “People also have difficulty with how they represent mixed dishes and the serving size of different ingredients in the dish.”

While not familiar with the MyFoodPhone service, she said it sounded like much less effort than a traditional program where you write down what you eat. And while a picture alone might not always allow a dietitian to calculate a meal’s calories, it would give “a much better idea of the portion size and what the meal contains,” Ms. Sandon said.

Leslie Bonci, director of sports nutrition at the University of Pittsburgh Medical Center, backed up Ms. Sandon’s assessment. She called MyFoodPhone’s $99 monthly fee “a bargain” compared with in-person consultation by a dietitian: “The initial visit will cost more than that.” (The $99 fee does not include the $10 to $20 you’d likely pay under your wireless service plan to e-mail pictures of a month’s meals. And, of course, you’d also have to provide your own camera phone.) Ms. Bonci serves as an adviser to a competing service called Nutrax (www.nutrax.com), which is still in a test phase and offers some cheaper options than MyFoodPhone.

MyFoodPhone itself launched its service only in February, Marc Onigman, its vice president of business development, said. The company has signed up 50 registered dietitians to act as advisers and has demonstrated its system to some health care providers and hospitals that Mr. Onigman said are considering offering it to members and patients.

Meanwhile, “about 100” people have subscribed, Mr. Onigman said. They have all stuck with the program so far – but the idea is for them to learn portion-control habits that will eliminate their need for the service entirely.

“It’s a different approach, it’s not really a diet in the conventional use,” he said. “It’s the throwaway line at the end of every story: Experts say that, you know, the best way to lose weight is to exercise more and eat less.”