While timing is key for gains, choosing a safe product is key for health. The supplement industry is vast, and not all powders are created equal. A narrative review in Healthcare (2024) highlighted several potential health risks associated with unchecked whey consumption.

There is a persistent fear that protein powders cause kidney damage in healthy individuals. Current evidence suggests that high-protein intake does not harm kidney or liver function in people with healthy organs. However, for those with pre-existing conditions (undiagnosed kidney disease or compromised liver function), excessive protein can indeed cause kidney strain and exacerbate problems. This is a case of medical contraindications where professional scepticism is warranted if you have a family history of kidney issues; get checked before starting high-protein diets.

Digestive issues are the most common side effect. Whey protein concentrate contains lactose, which can cause bloating, gas, and diarrhoea for the lactose-intolerant. Furthermore, "protein overload", consuming 70+ grams in a single sitting, can overwhelm the digestive system, leading to severe discomfort regardless of tolerance.

Perhaps the most alarming risk comes not from the protein itself, but from what is hidden inside the tub. Independent testing by organisations like the Clean Label Project has found that many protein powders contain heavy metal contamination (lead, cadmium, arsenic) and BPA. Additionally, many brands load their products with artificial sweeteners, fillers, and added ingredients that can trigger adverse reactions like headaches or allergic responses.