A 65-year-old Seattle woman is attempting to go 100 days on just water, shunning all medical advice in the process

Naveena Shine has lost 30lbs since beginning her experiment. Photograph: Facebook

A Seattle woman is attempting to go 100 days without eating to prove that humans can "live on light".

Naveena Shine says she believes it is possible for human beings to survive without food and is conducting what she describes as an experiment to prove it.

The 65-year-old, originally from Birmingham in the UK, has been consuming just water and "one, maybe two cups of tea a day" for the past 41 days, losing 30lbs in the process. Other people have previously claimed to be able to survive without food and and water, although no one has ever proven it to be possible and some have died attempting it.

Dr Ronald Hoffman, medical director of the Hoffman Center and host of a weekly health talk podcast, said it was "delusional to think that you can escape the laws of biology".

"Plants have what are called choroplasts that contain chlorophyll and they have the ability to capture energy from sunlight," Hoffman said. "Humans don't have cholorphyll or chloroplasts. No humans do. It is impossible for a human to have that.

"Therefore they have to derive energy from external sources, that can be either fat or protein or carbohydrates, but it can't be sunlight."

Hoffman said if Shine continues to not eat food her organs will eventually fail and she will die.

Shine contends that "a doctor can't see living on light because he looks through different lenses" and has said she is not undergoing medical tests as during the experiment. She said she had experienced a "calling" which inspired her to stop eating.

"It came as an idea that became so powerful, I knew I had to do it," she said. "And this has happened a few times in my life; I suddenly got this strong desire or need to do something that nobody in my world could imagine but it came so strongly to me, it was just like: 'This is what I need to do.' It's intuition."

She said she had heard of others who claim to be able to forgo conventional nutrition, including a friend who claimed to have survived without food for three years.

"I know that people say it is [possible] and I don't disbelieve them, and I don't believe them, so the only way to find out is to do it," she said.

Shine is not undertaking any special exercises or performing other procedures in order to "live on light" – a process she describes as "not necessarily literal".

In 2003 American illusionist David Blaine survived 44 days in a glass box without food, while last year a Swedish man claimed to have survived two months in his car eating just handfuls of snow. While experts believe it is possible for the human body to survive for up to two months without food, should Shine survive for 100 days her feat would be unprecedented.

"It is said by scientists that all matter comes from light. All matter," she said. "It does go through all of our animals and grass all the things that grow on our planet so that we can access it. But that doesn't mean to say that we don't have a system within us already that can access it more directly."

While Shine says her inspiration to eschew food does not come from a particular set of beliefs, her website praises Jasmuheen, an Australian woman who describes herself as an "ambassador of peace" and "international lecturer", and whose teachings that it is possible to subsist on light alone have been linked to the deaths of four people.

Jasmuheen claims to have lived for years on light alone, but tried and failed to go without food and water for 10 days in an experiment for Australian television program 60 Minutes in 1999. A doctor for the network noted that after 48 hours Jasmuheen displayed symptoms of dehydration, stress and high blood pressure. The network cancelled the experiment after four days when Jasmuheen's health continued to deteriorate.

So far Shine has lost 30lbs, although in a post on Facebook she said her weight has "been holding at around 128lbs and 129lbs". In video updates posted to Facebook and her website she has reported feeling light-headed when bending down and when getting up from a seated position. She said she had a couple of days where she threw up bile, but other than that was in good condition.

The tone of her Facebook updates has changed as time has elapsed, with it appearing this week that Shine would not put herself at risk if she continues to deteriorate. On Monday she wrote that she would not drop down below 120lbs; suggesting an end to her attempt may be in sight.

She said she had started adding "a package of EmergenC" into her water, which she said had no nutritional value, although the website of the supplement shows that a typical package does contain 25 calories and a number of vitamins and minerals.

Beyond that, however, Shine has eschewed medical evaluations.

"Doctors can't really have that much to say with this, because it's not within the doctors' paradigm. A doctor can't see living on light because he looks through different lenses, he looks through different eyes.

Certainly if I start getting ill or I start falling all over the place or I start feeling really bad or all the things that are pretty obvious, I will know that this is not going anywhere and I can stop, which I will. But so far none of that's happened."

Hoffman said he would urge Shine to begin the "slow reintroduction of food".

"Stop doing it, and get some medical tests to see if there's any critical deficiencies, because critical vitamin deficiencies can develop too. It's not just protein and calorie, it's also there may be critical deficiencies of D vitamins, vitamin C, you could get scurvy. All the nutritional diseases can manifest when you don't eat."