If you've been anywhere near health TikTok or wellness Instagram lately, you've probably seen influencers swearing by the "sardine fast." The trend promises detox, weight loss, and better brain health, all from eating nothing but sardines for 24 to 72 hours. While it is minimalist and high-protein, it's not great.
Registered Dietitian Emily Van Eck, MS, RD, isn't buying it, and she wants you to think twice before jumping on the sardine bandwagon. "There are no benefits to following this diet," Van Eck says bluntly. And she's not wrong. While sardines pack a nutritional punch, a mono-food fast like this one isn't the miracle cure social media makes it out to be. In fact, it might be doing more harm than good.
Why Sardines Got the Wellness World Hooked
Let's give credit where it's due. Sardines are a nutritional powerhouse. These small, oily fish are rich in Omega-3 fatty acids (great for heart and brain health), high-quality protein, Vitamin D and B12, calcium, and selenium.
They're also budget-friendly, shelf-stable, and sustainably sourced, so it's no surprise they've become a darling of the wellness scene. The problem is that turning them into a short-term, single-food fasting trend strips away all the nuance of actual nutrition.
The Problem With the Sardine Fast
Your body isn't designed to thrive on just one food, even a healthy one. Van Eck explains that eliminating all other foods can harm your relationship with food and deprive you of essential nutrients like fiber.
The sardine-only approach lacks fiber, which supports gut health and digestion, complex carbohydrates, which are essential for energy and brain function, and phytonutrients from fruits and veggies. Not to mention the mental toll of restricting your intake so severely. "Any time a diet encourages cutting out entire food groups or promotes short-term restriction, it's a red flag," Van Eck adds.
This kind of rigid eating can mess with your hunger cues, lead to rebound eating later, and foster an all-or-nothing mindset that's tough to shake.
What to Do Instead
Here's the good news! You don't have to throw out the sardines altogether. Van Eck actually recommends keeping them on your plate, just not as the only thing on your plate. "Tinned fish is a fantastic addition to a balanced diet," she says.
Instead of a sardine fast, think of ways to add sardines to your meals in satisfying, balanced, and sustainable ways. Try sardines on whole-grain toast with smashed avocado and arugula or sardines tossed into a Mediterranean-style salad with olives, chickpeas, and tomatoes.
Another meal idea is to mix sardines into pasta with lemon zest, capers, and herbs, and add them to grain bowls with roasted veggies and tahini dressing. This way, you'll reap the benefits without falling into a disordered eating pattern.
Viral Diets Aren't the Answer
Trendy eating plans thrive on extremes. They're clickable, shareable, and easy to market as quick fixes. But they rarely lead to lasting health and often come at the cost of your well-being.
Van Eck's approach is practical, inclusive, and evidence-based. Nutrition isn't supposed to be a punishment. It's a long game, and that means building habits that feel good and support your body. The goal should be sustainable, nourishing choices, not deprivation in disguise.
The sardine fast might look clean and trendy on social media, but it's a nutrition myth dressed up in wellness lingo. Sardines are healthy, yes—but eating only sardines is not.