Someone told me recently about the Jared Fogle story and his subway diet (I didn't know about it since there was no Subway in my country by that time).
Is/Was it really healthy ?
Your question is kind of vague - what is "healthy"?
Subway diet is unquestionably healthier than Jared Fogle's previous "high-fat junk food" diet, especially coupled with increased physical exercise.
However, it is not considered to be dietitionally/nutritionally perfect by any stretch of imagination.
Not only there is no research supporting the diet as perfect, here's a quote from Subway's corporate dietitian accompanying the news release about the promotion:
Both Jared Fogle and a Subway Corporate dietitian acknowledged that some elements were missing from the weight-loss plan designed by the Indiana college student. “It's great that it worked for him, but I would rather he had eaten a balanced breakfast and more fruits and vegetables,” dietitian Lanette Roulier said in a December 2000 news release.
She pointed out that people's dietary needs varied, and advised the public to consult with a physician and/or dietitian before starting a weight-loss program.
A restrictive diet of only two sandwiches a day is not nutritionally sound. Jared Fogle eliminated fruit and dairy products from his diet. He missed out on the fiber in fruit and nutrients like vitamins A and C. The diet also lacked the calcium found in dairy products.
However, the sandwiches provided fiber and vitamins. Poultry like turkey was among the lean proteins recommended in the USDA guidelines. The federal guide also advised people to limit fat and to participate in regular physical activity. Fogle did both.
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