A leading longevity doctor has revealed the diet he says may be able to cure cancer, and potentially ward it off in the first place. 

There is increasing evidence that severe calorie restriction (fewer than 800 calories per day) can deprive cancer cells of the nutrients they require to proliferate, effectively stopping their growth and destroying them.

The challenge? Research indicates that even the most committed individuals find it difficult to maintain such extreme dietary deprivation, and there may be unintended health effects, such as muscle wasting and infertility.

Dr. Valter Longo, director of the Longevity Institute at the University of Southern California, has now developed a diet that ‘mimics’ these effects by deceptively signaling the body into a fasting state while still permitting food intake.

A fasting-mimicking diet (FMD) consists of mostly plant-based foods, foods low in protein and sugar and rich in healthy, unsaturated fats, such as avocados, fatty fish (tuna, salmon, sardines), olive oil, eggs, seeds and nuts (almonds, cashews).

Dr Longo recommends following an FMD cycle once a month to once every three or four months.

This ‘tricks’ the body into thinking it is fasting without denying it food, and by doing so, makes cancer cells weak and vulnerable, allowing treatments to be more effective. 

Dr Longo explained that a fasting-mimicking diet, ‘promotes changes in the body equivalent to those caused by water-only fasting.’

Dr Valter Longo, pictured, is the director of the Longevity Institute at the University of Southern California

However, experts caution that FMDs should only be done under the close supervision of oncology dietitians to avoid complications like muscle wasting and immune system compromise, saying the diets are ‘not a silver bullet’ cancer cure. 

‘While we have learned that you cannot starve cancer with fasting alone… you can use fasting-mimicking diets to make the cancer cells so weak or desperate that the right therapy will kill them,’ Dr Longo said.

‘The ability to block cancer cells from rewiring and escaping the toxicity of the treatment is what makes the fasting-mimicking diet a very promising wild-card therapy.’ 

Some dishes included on his Recipes for Longevity website include anchovies with endive, stuffed artichokes, chickpeas, onions in walnut sauce, snapper, sardines, hummus and octopus.

In his book, Fasting Cancer, Dr Longo detailed research on extreme calorie-restricted diets tested in mice, primates and people that ‘demonstrates that many cancers can be prevented by chronic calorie restriction.’

However, because the diet ‘is very difficult to follow and it is accompanied by severe weight and muscle loss, it is not feasible for most people.’

Additionally, he wrote, multiple studies ‘indicate that many and possibly most cancers can be prevented by dietary restrictions affecting growth genes.’

But the diets can’t include ‘chronic calorie restriction since they must be feasible and cause minimal or no side effects.’ 

Alison Tierney, a board-certified oncology dietitian and cancer survivor who water-fasted throughout chemotherapy treatment, told the Daily Mail there is growing scientific evidence supporting FMDs, ‘especially in the context of cancer’ because they ‘stimulate the metabolic effects of fasting while still allowing some caloric intake.’

‘FMD or water-only fasts are not appropriate for everyone,’ she said. ‘If a patient is considering a fasting protocol, it’s essential they work closely with their oncology team and a board-certified oncology dietitian. 

‘Together, they can assess medical history, current nutritional status, and treatment goals to determine if fasting is a safe and supportive option.

‘If it is, ongoing monitoring is critical. FMD and water only fasting protocols often need to be adjusted throughout treatment to ensure they support – not compromise – healing and strength.

‘So yes, fasting may be helpful in some cases. But it has to be done safely and individually.’

Tierney added that calorie restriction can be risky during cancer treatment as it can lead to malnutrition, muscle wasting, fatigue, suppressed immune function and delayed wound healing – ‘all of which are serious when the body is already under stress.’

‘Even FMDs, while generally safer [than water-only fasting], can come with challenges like unintentional weight loss, low energy, dehydration or inadequate nutrient intake, especially without proper guidance,’ she added.

‘That’s why a personalized approach is key.’

Dr Longo recommends eating for 11 to 12 hours per day and fasting for 12 to 13 hours per night, as opposed to the more restrictive intermittent fasting regimen of eating for eight hours and fasting for 16 hours. 

The diet consists of foods low in protein and sugar and rich in healthy fats, such as avocados, fish, olive oil, eggs and nuts

Additionally, the doctor said his research has found a way to use a combination of standard therapies and the FMD to fight a patient’s cancer by taking advantage of the different ‘needs’ of cells. 

While normal cells need sugar to function, they can operate on a much lower level, while cancer cells thrive on high levels of sugar. 

‘This is where nutrition and evolutionary biology meet oncology,’ Dr Longo writes. 

And while diet and nutrition have long been viewed as lesser-than therapies, a cancer patient’s care team needs to embrace a more holistic treatment plan – integrating both the traditional oncology and nutritional-based therapies. 

‘We should reconsider this outdated mentality and instead provide patients with the type of 360-degree care and multidisciplinary team that can maximize the chance of a cure but also improve healthy longevity,’ Dr Longo wrote.

Using only drugs to treat cancer ‘is like fighting a war by only employing the infantry. We need to fight tactically by thinking differently about the problem.

‘Nutrition was and still is viewed by many doctors as a “palliative” intervention, not really effective against the disease but possibly helpful to make the patient feel better or more involved in their care. 

Alison Tierney (pictured), a board-certified oncology dietitian, told the Daily Mail there is growing scientific evidence supporting fast-mimicking diets

‘Fasting and the fasting-mimicking diet are viewed the same way and get the same treatment as “fruits and vegetables” or “having a healthy diet.”‘

Tierney told the Mail ‘Nutrition should support the body’s ability to heal and recover – not compromise it.

‘FMD can be a complementary tool in cancer prevention or treatment for the right individual, but it’s not a one-size-fits-all solution.’

With breast cancer, the second most common cancer in women, one study found mice who had undergone an FMD in combination with chemotherapy had immune cells (activated by the diet) that penetrated the tumor and killed the cancer cells.

Results indicated the combination of diet and chemo is more effective that just using one of the two.

With colon cancer, Dr Longo’s research showed any type of fasting did not weaken cancer cells when used alongside common chemotherapy drug doxorubicin. 

However, when used in combination with more targeted cancer drugs, the FMD made the drug more effective.

Results like these support Dr Longo’s research that shows patients should have a personalized FMD, which triggers ‘many coordinated changes’ in the body that kill cancer cells while protecting healthy cells from the toxic drugs.   

With this personalized diet, calories, ingredients and frequency of diet cycles are carefully designed and monitored to achieve the best anti-cancer effects, especially in relation to medications the patient is taking. 

‘As a board-certified oncology dietitian and cancer survivor, I believe nutrition is one of the most empowering tools we have in this journey,’ Tierney said.