Sardines are a nutrition powerhouse, rich in protein, omega-3s, vitamin D and calcium, all vital for heart health, strong bones and a solid immune system. But what happens when you ditch everything else and eat nothing but the oily fish?
Sardine fasting is exactly what it sounds like: eating only sardines for a set period of time. There are no strict rules, just tins on tins of fish. The concept first surfaced in 2012 when Dr Frederick Hatfield, known as “Dr Squat” after becoming the first person to squat over 460kg in competition, began incorporating sardine-only fasts into his ketogenic diet while battling cancer.
The trend resurfaced after Dr Dominic D’Agostino discussed it on The Tim Ferriss Show podcast. Since then, it’s been popularised by Dr Annette Bosworth (aka Dr Boz), who claims eating six cans a day for 72 hours can “reset” your metabolism.
Is Sardine Fasting a Health Hack?
While sardines are undeniably healthy, relying on them alone isn’t. They lack fibre, complex carbohydrates and several key vitamins, setting you up for digestive issues, low energy and brain fog.
Cancer Research UK points out there’s “no evidence” that cutting out certain food groups, like sugar or carbs, can reduce cancer risk or improve survival outcomes. In fact, overly restrictive diets can harm your long-term health by eliminating foods that provide essential fibre and nutrients.
READ MORE: A High-Fat Diet Might Be the Brain Boost You Didn’t Expect
And it’s not just about nutrition. Extreme eating plans can damage your relationship with food and even affect your mental health.
Then there’s the arsenic risk. In 2023, Joe Rogan said he found traces of arsenic in his blood, not from foul play, but from his habit of eating three cans of sardines every night. When he stopped, his levels returned to normal.
While a few fans of the diet swear by it, there’s no solid science backing sardine fasting’s supposed benefits. Without real studies, it’s impossible to know whether any positive effects are genuine or just placebo.
Why You Don’t Need to Sardine Fast
Ask yourself: do you really want to spend three days eating nothing but sardines? If you do, talk to your doctor first. But if the thought of your eighth tin turns your stomach, skip it.
While Dr D’Agostino says Hatfield used sardine fasting to manage cancer, most people today try it for weight loss. Dr Boz promotes it as a “fat-burning reset,” but there are far more enjoyable and sustainable ways to reach your goals.
READ MORE: Brain Boost: How Eating This Everyday Ingredient Can Sharpen Your Mind
Research published in the Journal of Obesity and Metabolic Syndrome found there’s no single “best” diet for weight loss. Success depends on what you can maintain long term.
Bottom line: sardines are great in moderation, whether you add them to a salad, pasta or pap, but surviving solely on tins is a fast track to burnout, not better health.
This article by Ryan Dabbs was originally published on Men’s Health UK
