UK doctor warns of grim side effects as woman eats only sardines for three months

A UK doctor is warning of the grim side effects as a woman ate only sardines for three months.

Yep, imagine that, tins of the oily fish and nothing else – not even a bit of pasta to mix it in or some, you know, fruit and veg.

Keto influencer Annette Bosworth popularised the viral 72-hour sardine fast, with one woman getting so hooked she kept it going for much longer.

Jane Crummett was struggling with extreme foot pain, inflammation and food addiction when she opted for a carnivore diet.

But when her weight starting going back up, she decided to try the controversial method from ‘Dr Boz’.

Jane Crummett said people think she's 'nuts'. (YouTube/Dr. Boz [Annette Bosworth, MD])

Supposedly, her sardine fast is supposed to improve health by jump-starting metabolism and sending the body into advanced ketosis to rapidly burn fat for energy.

Crummett confessed that people think she’s ‘absolutely nuts’ but claims the diet has restored her energy, reduced her blood sugar and relieved her pain.

The 62-year-old retired military therapist consumed four cans of the oily fish every day and supplements with MCT oil.

But NHS GP Dr Masarat Jilani, who works with bladder care company Jude, explains why you should be wary of this sardine-only diet.

While she says there ‘is a lot of nutritional good’ in the fish, ‘eating sardines alone is not a healthy choice’.

“Firstly, they contain zero fibre. Fibre is crucial for gut health and digestion. A diet based solely on sardines could lead to constipation,” the doc says.

Jilani also explains that the way sardines are packaged up ‘means they are usually preserved in either salt or oil’.

The doc warns it could make you pretty constipated (Getty Stock)

“If they are salted sardines, you will be consuming an excessive amount of sodium, which can raise your blood pressure and put strain on your kidneys,” she adds.

“They also contain heavy metals and mercury—though not in the same amounts as larger fish.

“Sardines are generally low in these contaminants. However, if consumed in large quantities over time, the accumulation of these trace metals could still be a concern, especially as part of a sardine-only diet or fast.”

Yep, potential constipation and strain on your kidneys as well as a concerning accumulation of trace metals are all risks Jilani warns of from this diet.

And of course, the NHS stresses the importance of a healthy, balanced diet to help maintain good health including at least five portions of fruit and vegetables every day.

If you’ve got concerns about your diet, it’s important to speak to a doctor or registered dietician before deciding to try something like eating nothing other than cans of fish.