Low-carbohydrate diets have surged in popularity over the past few decades, praised by many for their potential health benefits, from weight loss to improved blood sugar control. Yet, they’ve also become a lightning rod for misinformation and confusion—fuelled by conflicting research, sensational media headlines, and outdated nutritional dogma.

A recent review published in Nutrients (March 2025), titled “Myths and Facts Regarding Low-Carbohydrate Diets”, provides a clear-headed, evidence-based summary of what we really know—and don’t know—about low-carb eating. Here’s a closer look at the key insights.

What Is a Low-Carbohydrate Diet, Really?

One of the first hurdles in discussing low-carb diets is defining what we mean by “low-carb.” This paper adopts the standard scientific definition:

• Low-carbohydrate diet: ≤130g of carbs per day, or <25% of daily calories
• Ketogenic diet: 20–50g of carbs per day, or <10% of daily calories

This clarification helps draw a line between modest carb reduction (like many “clean eating” plans) and true ketogenic diets designed to induce a state of nutritional ketosis. The latter requires more careful planning and has more pronounced metabolic effects.

Busting Common Myths

The review tackles some of the most frequently cited criticisms of low-carb diets head-on.

1. 

“Low-carb diets are nutritionally inadequate”

This is a pervasive myth. Critics often suggest that restricting carbohydrates inevitably leads to nutrient deficiencies, but the evidence doesn’t support this—at least not when the diet is well-designed.

A low-carb diet based on whole foods—such as vegetables, meat, fish, eggs, dairy, nuts, seeds, and healthy fats—can provide all essential nutrients. The authors even include a “low-carb food pyramid” to illustrate this point, showcasing the diversity of foods available.

2. 

“Low-carb equals high protein”

Another common misconception is that a low-carb diet must be high in protein. In reality, protein intake on a low-carb diet can range from moderate to high, depending on individual goals and preferences. What tends to increase more dramatically is fat intake, especially in ketogenic diets.

3. 

“Low-carb diets are bad for the heart”

Perhaps one of the most hotly debated topics, this concern is rooted in the assumption that eating more fat (especially saturated fat) increases cardiovascular risk. However, clinical studies reviewed in the article show that low-carb diets can actually improve several key heart health markers, including:

• Lower triglycerides
• Higher HDL (“good”) cholesterol
• Reduced small, dense LDL particles (a riskier LDL subtype)

These changes may contribute to a reduced overall cardiovascular risk—though individual results can vary.

4. 

“Keto flu is dangerous”

The so-called “keto flu”—characterised by fatigue, dizziness, headaches, and irritability during the first few days of carb restriction—is real but temporary. The paper explains that this is due to electrolyte imbalances, especially sodium loss, as the body shifts from burning glucose to burning fat.

The solution? Increasing salt and fluid intake can often mitigate or eliminate these symptoms.

What the Evidence Really Says

The authors of the review emphasise the importance of clinical trial data over observational studies. Observational research is prone to confounding factors and doesn’t prove causation—an important distinction in nutrition science.

What they find is that:

• Low-carb diets consistently outperform low-fat diets for weight loss in the short term (up to 6–12 months).
• Glycaemic control improves, making low-carb diets particularly useful for people with type 2 diabetes or prediabetes.
• Inflammation markers and blood pressure may improve, particularly when refined carbs and sugars are reduced.

Personalisation Is Key

Despite these findings, the authors stop short of recommending a low-carb diet for everyone. Nutritional needs vary, and no single diet suits all. Instead, they advocate for personalised nutrition, with dietary choices tailored to individual health goals, preferences, and medical history.

For those considering a low-carb or ketogenic diet, the paper advises working with a knowledgeable healthcare provider—especially if managing conditions like diabetes, where medication dosages may need to be adjusted.

Takeaway: Low-Carb Isn’t a Fad—It’s a Legitimate Option

This review is a breath of fresh air in the nutrition space. It strips away the ideological noise and looks squarely at the evidence. Low-carbohydrate diets, when done right, are not only safe but can be highly effective tools for managing weight, blood sugar, and metabolic health.

They’re not magic. They’re not for everyone. But they are worth understanding—and for many, they might just be the approach that works.