Low-carb diets have been around for decades—and keto is the poster child for low-carb, high-fat (LCHF) diets right now.
Once it was Atkins', and then it was Mediterranean or Nordic, and now we're back around to a low-carb diet that shifts to fat as the primary fuel source.
There's a lot of enthusiasm out there, but it's important to be realistic. Diets work by trade-offs: fewer carbs means you have to make up for it somewhere else.
Sometimes, that requires attention and effort to avoid nutrient deficiencies—and low-carb diets are strong examples of that problem.
Today we're going to look at what nutrients are missing from a low-carb diet—why they matter so much, and what you should do about it. The idea is to outline and solve problems.
What's At Risk In Carb Restriction?
These diets all have their ups and downs—the trade-offs. The problem that we see here is that this cuts out some of the most critical and nutrient-dense groups of foods in a diet.
This is common with the 20-50g of carbs you see in diets like Keto, the Nordic diet, and the Mediterranean diets.
So, what do these low-carb diets miss out on?
The problem facing low-carb diets is restriction. If I force you to cut out or restrict any food group, you're going to be at some risk.
The science is clear: removing carbs from the diet reduces the intake of crucial wellbeing factors like fiber and essential minerals—while performing better on others.
The risks of nutrient deficiency come from restricting some of the healthiest carb sources along with the total restriction: wholegrains like oats, beans, and legumes, alongside higher-carb vegetables like carrots and tomatoes.
Why Deficiency Is A Real Concern
Deficiency in minerals isn't only a concern for optimizing your diet—but for the proper and basic health of your body and mind. These crucial nutrients are associated with the worst effects of low-carb diets, independent of optimizing metabolism and performance.
Deficiency in the key nutrients mentioned here—specifically the minerals and electrolyte group, is one of the major causes of adverse events.
Things like "keto flu"—a short-term adaptation syndrome associated with fatigue, migraines, and digestive problems—result from these nutritional deficiencies.
This is also a problem in recovery where carbohydrate intake restriction, independently of the vitamins or minerals, can stunt muscular growth.
The mTOR pathway that drives muscle protein synthesis, which is the basis for recovery and growth, is directly suppressed in LCHF diets like keto.
However, these can affect you at any time, not just during the first weeks of a low-carb diet.
Any time you dip below the required levels of vitamins and minerals, you're at risk. This has some carryover to other areas, like the ability to sustain performance in active careers or a feeling of energy deficit throughout the day.
Which Nutrients Are At Risk?
While high-quality meats and fats are rich in some B vitamins, low-carb diets tend to struggle with others.
Folate, which is usually found in starchy vegetables, can easily be missed out—which is crucial for healthy energy metabolism in your cells.
Minerals are underrated despite propping up some of the most important processes in the body.
They're also common concerns for nutrient deficiency in keto since foods rich in minerals—like wholegrains and legumes, are restricted in low-carb diets.
The main things you're at risk of missing out on are potassium and magnesium. Potassium works as part of the balance with sodium for health in countless systems, and low sodium-to-potassium ratios put your heart and bone health at risk.
For example, electrolytes fuel muscles and help with hydration, while specific compounds like calcium can be great for bone health, and magnesium and zinc are critical for metabolic wellbeing.
These include (among many others) metabolism, muscular function, hormonal wellbeing, and regulating mood and fatigue.
Fiber is key here: it's a way of regulating your metabolic and digestive health using your diet. These are found in high-quality carbs and restricting their intake has knock-on effects on these systems if you're not careful.
Hope: What's the Solution?
Fortunately, none of these deficiencies are set in stone. Low-carb diets don't have to fall flat on fiber, folate, or minerals. It's about the planning and effort that goes into these diets.
Proper Planning Is Key
You can't half-effort a low-carb diet. Much like other forms of restrictive diet, it has to come from a place of planning and forethought.
The difference between the benefits seen in studies on low-carb diets and the real-world failures are the forward-planning and regulation.
If you're closely limited in your choice of food and the number of carbs you can eat, they all need to serve a purpose. You need to be conscious of these nutrients.
Accept, also, that there will be a drop-off in your ability to perform and recover from exercise.
Ketosis is a process of making up the deficiency in carbohydrate intake, and it's a weight-loss diet. Don't try to get big and strong on keto—the much slower pace will disappoint you.
Food Sources
You should also focus on the low-carb sources for the main vitamins and minerals you're going to be struggling with. They're not impossible; they're just challenging.
Foods like nuts and seeds can make up many of the electrolyte differences. Cultured dairy also offers many of these nutrients, specifically the electrolytes like calcium.
Proper food sources are crucial for preventing these significant concerns. You need to select every food source—fats, protein, and carbs, for micronutrient density.
Since fats and protein sources will define your diet, they need to take up the slack from missing nutrient-rich carb sources.
The carbs you eat on a low-carb diet need to be very nutrient dense. Leafy green vegetables, for example, are there to make up the nutrient deficit while being calorie- and carb-sparse.
Eyes on Fiber
Fiber is a good indicator of a carb source's quality and something you need to pay attention to.
If you're not paying attention to the fiber in your diet, the whole thing gets harder.
The metabolic and digestive regulation fiber provides is important to making a low-carb diet work, especially since you're increasing your intake of fats—which can cause digestive distress without proper fiber.
Fiber needs to come from leafy greens, which are low in digestible carbs, nuts, and seeds. Your options are severely restricted by carb restriction, and you need to get as many as possible for your daily carb allowance.
Summary & Key Points
The things that make for a good low-carb diet are the same as any other diet; they just have the additional challenges that come with restriction.
The range for error is very tight, and each component in a meal needs to do some work on making up the nutrient deficit.
If you're willing to be smart about your diet and plan ahead, making the best use of each food group, you can make up this difference and avoid the major issues.
The other half of it is accepting the differences and trade-offs that come with low-carb diets: it's not a performance diet, it's not for getting big, and it means a little metabolic disadvantage.
Whatever your diet looks like, apply these priorities of food source choices and the right kind of vitamins and minerals. They support health, but they also help you build a better performance profile—mentally and physically.
References
- Proper micronutrient adjustments improve common LCHF diets: https://doi.org/10.1186/1743-7075-5-11
- Keto inhibits mTOR: https://doi.org/10.1111/j.1528-1167.2011.02981.x
- Nutritional differences in HC and LCKD: https://doi.org/10.3390/sports7090201
- Folate deficiency prevalence in ketosis and LCHF diets: https://doi.org/10.1093/ajcn/86.5.1773
- The role of fiber in human health and nutrition: https://doi.org/10.1111/j.1753-4887.2009.00189.x
