UPDATED BY FRANZISKA SPRITZLER, RD, CDCES
For decades, we’ve been told that carbohydrates – especially whole grains, legumes, and brown rice – should form the foundation of a healthy diet. Since the 1990s, government guidelines have reinforced this message, encouraging us to fill our plates with bread, pasta, and other starchy foods. But growing research and rising rates of metabolic disease tell a different story. It turns out that many of the claims about carbohydrates (carbs) and fat were based on outdated or incomplete science. To truly support health, it may be time to rethink what a “balanced diet” really means.
How Did We Get Here?
Our carb-focused view of “healthy eating” didn’t just happen; it was driven by the low-fat movement of the 1980s. Fat was widely blamed for heart disease, and low-fat diets quickly became the norm. Food manufacturers seized the opportunity, cutting fat from products and replacing it with sugar and refined carbs to maintain taste and texture. Grocery stores soon filled with processed foods marketed as “healthy,” despite being loaded with ingredients that spiked blood sugar and offered little nutritional value.
As noted in the Journal of the History of Medicine and Allied Sciences, “Driven by consumer demand and widespread advertising, in the 1980s and 1990s, low-fat industrial foods proliferated to fill grocery store shelves. The release of the USDA’s first food pyramid in 1992 solidified this mindset, officially endorsing a low-fat, high-carb diet, even as controversy surrounded its development.”
The impact of this shift went far beyond food labels. By promoting grains and starches as dietary staples, the food pyramid steered Americans toward a carb-heavy pattern of eating. Over time, this high intake of refined carbohydrates and processed foods contributed to a rise in chronic conditions like obesity, insulin resistance, and other forms of metabolic dysfunction.
Why Carbs Aren’t Essential
According to the US National Academy of Sciences, essential nutrients include water, energy, amino acids (from protein), essential fatty acids (from fat), vitamins, minerals, electrolytes, and trace elements. What’s missing? Carbohydrates. The Academy even states: “The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed.”
Let that sink in. The food pyramid we grew up with – the one placing grains at the base – wasn’t just misleading. It was upside down.
To better understand why this is the case, let’s first get a simple understanding of what carbs are.
What are Carbs, Really?
Carbohydrates include sugars, starches, and fiber. They fall into two main categories: simple and complex. Simple carbs are made of short sugar chains and are found in foods like sugar, candy, fruit, and even some vegetables. Complex carbs have longer chains, take more time to break down, and are found in foods like bread, pasta, and cereals.
Are complex carbs better for you? Generally, yes. Because they’re digested more slowly and contain fiber, they lead to a more gradual rise in blood sugar and insulin levels. That means fewer spikes and crashes.
But here’s the bottom line: whether simple or complex, all digestible carbs break down into glucose. That glucose is first used for immediate energy or stored as glycogen in the liver and muscles. Once those glycogen stores are full, excess glucose can be converted into body fat.
Should We Avoid Carbs Altogether?
Our bodies can function well with little to no carbohydrate intake, and in many cases cutting carbs improves metabolic health. But does that mean you need to eat zero carbs? Not necessarily.
Unless you are on ketogenic metabolic therapy for a medical condition, you can consume around 20 net carbs per day on a keto diet regardless of your optimal macros. But the goal isn’t just to cut carbs; it’s to choose the right ones.
If you include carbs, focus on above-ground vegetables like spinach, broccoli, cauliflower, zucchini, and peppers. These are low in digestible carbs, packed with nutrients, and have a minimal effect on blood sugar.
And remember, net carbs are different from total carbs. You calculate them by subtracting fiber (and some sugar alcohols) from total carbs, since fiber isn’t digested or absorbed in your intestinal tract. Learn more about net carbs here.
Want help tracking your carb intake? Keto-friendly apps can make it easier. We review some helpful ones here.
The Importance of Dietary Fat
So where does energy come from if you’re not eating many carbs? The answer is fat. Not only is fat an efficient fuel source, but it also supports brain function, along with hormone production and immunity, among other functions.
But quality matters. Highly processed fats, such as industrial vegetable or seed oils, should be minimized or avoided. It’s also important to keep your intake of omega-6 fatty acids (highly concentrated in vegetable oils) in check, because high amounts combined with inadequate intake of omega-3 fatty acids (found in fatty fish, flaxseed, and chia seeds) may promote inflammation. Focus on healthy, natural fats instead. Good options include coconut oil, extra-virgin olive oil, macadamia nut oil, avocado oil, avocados, nuts, and animal fats like lard, tallow, and bacon fat (from healthy sources). These fats can help keep you energized, satisfied, and metabolically healthy.
Using Fat for Energy
When you eat a high-carb diet, your body relies on glucose for energy. Carbs are broken down into sugar, which raises insulin and leads to glycogen storage in the liver and muscles. Excess glucose, beyond what the body can store as glycogen, is stored as fat.
But when carbs are very limited, as on a ketogenic diet, your body turns to fat for fuel. The liver breaks down fatty acids from food and body fat into ketones, a clean, steady energy source. This state is called ketosis.
Think of it like this: carbs are kindling. They burn quickly and need constant replenishment. Fat is the log on the fire. It burns slowly and steadily, keeping your energy stable for hours. To tap into that steady burn, carbs must be low enough for ketones to take the lead.
In addition to providing your body and brain with fuel, ketones have other beneficial effects. Learn more in our article Four Functions of Ketones Beyond Fueling Your Body.
The Final Word
Despite what we’ve been told for years, carbohydrates aren’t essential for health or brain function. In fact, many people feel and perform better on a very low-carb or ketogenic diet. That said, it’s always wise to consult with your doctor or a registered dietitian before making significant changes to your eating plan, especially if you have a medical condition or take medication.
