How many genes are in the human genome and why the count matters for health and biology

How many genes are in the human body anyway? A quick question, a big idea, and a lot of nuance tucked in between.

If you’re navigating the world of nutrition science—especially topics that pop up in NAFC-related material—you’ll hear that our bodies are built from about a certain number of genes. The simple version is: there are roughly 35,000 genes people sometimes mention. But the longer, truer story isn’t a single number you memorize and file away. It’s a moving target that helps you appreciate how genetics and nutrition intersect in real life.

Let me explain the big picture first.

What counts as a gene, and why the numbers aren’t fixed

Think of a gene as a block of information that can guide a cell to make something it needs—often a protein, sometimes a regulatory molecule. When scientists talk about “the gene count,” they’re usually focusing on protein-coding genes, the ones that carry the instructions for making enzymes, transporters, and other workhorse proteins that keep cells humming.

• Protein-coding genes: estimates run about 20,000 to 25,000. That’s the blunt core—the genes you can point to and say, “this is the blueprint for this enzyme or transporter.”

• The rest of the genome: there are many non-coding genes and regulatory elements that help control when, where, and how much those proteins get made. These aren’t silent or useless; they’re the conductors in the orchestra, guiding gene expression so that metabolism responds to meals, fasting, stress, and exercise.

Because researchers keep refining genome annotations, you’ll see numbers like 30,000 or 35,000 tossed around in some contexts. The 35,000 figure isn’t a lie per se; it’s a reflection of broader counting methods or newer discoveries in non-protein-coding regions. What matters more for practical understanding is this: protein-coding genes sit in a core zone around 20k–25k, with a larger extra layer of regulatory pieces that push the total count higher in some tallies.

In plain terms: the headline number might vary, but the takeaway is simple—humans carry thousands of gene instructions, and many more regulatory elements tell those instructions when to wake up and work.

Why this matters for nutrition in everyday terms

You don’t need a lab coat to feel the relevance. Nutrition is a field of action—what you eat, how your body handles it, and how someone’s unique biology responds over days, weeks, and seasons. Genes don’t dictate every choice or outcome, but they shape tendencies:

• Metabolic tempo: Some people metabolize certain nutrients a bit faster or slower. Genetic differences in enzymes and transporters can influence how quickly you process fats, caffeine, or carbohydrate flux after a meal.

• Appetite and energy use: Regulatory genes affect hunger signaling and energy expenditure. That doesn’t seal someone’s fate, but it can tilt the balance toward different patterns of intake and activity.

• Nutrient needs and risk modifiers: Variants can tweak how efficiently you absorb minerals like iron or vitamin D, or how your body handles glucose. Knowing about these tendencies can inform personalized nourishment strategies.

This is the core idea behind nutrigenomics—the study of how gene-nutrient interactions influence health outcomes. It’s not about one perfect diet tuned to a single gene. It’s about recognizing the spectrum of genetic influence, and then pairing that with lifestyle signals to support each client’s well-being.

A small tour of real-world examples (kept practical)

Let’s anchor this with relatable examples you might hear in the counseling room or in general health discussions:

• Caffeine metabolism (CYP1A2): People vary in how quickly they break down caffeine. Some metabolize it fast, others more slowly. Your genetics can help explain why caffeine affects sleep, anxiety, or energy for some in the morning and not others in the afternoon.

• Lactose tolerance (LCT): Some folks retain the ability to digest lactose into adulthood, while others don’t. This difference often shows up as a preference or tolerance for dairy, and it can shape dietary choices without turning nutrition science into a mystery.

• Fat storage and appetite (FTO, MC4R variants): Certain variants have been linked to differences in energy intake and body weight regulation. Again, this doesn’t doom or guarantee outcomes, but it can smooth the path toward personalized guidance that respects an individual’s biology.

In coaching terms, these examples translate into practical questions you can discuss with clients: How does caffeine affect this person’s sleep? Is dairy a comfortable option, or should alternatives be explored? How might genetics align with a client’s preferences, activity level, and goals?

A clear mental model you can carry into conversations

Here’s a simple way to picture it: genes are the hardware, and the lifestyle you lead is the software. The hardware provides the capability—like a car that can run on different fuels. The software (your meals, timing, sleep, stress, activity) decides how efficiently you use that hardware. Sometimes, minor tweaks in the software yield big benefits. Other times, a larger reframe is needed. Either way, the goal is harmony between biology and daily choices, not one-size-fits-all rules.

So, what about the “35,000 genes” number you might hear?

• It’s a popular shorthand, but it glosses over the nuance. If you’re talking about the total gene count, some sources cite around 35,000. If you’re talking about the core protein-coding set, it’s closer to 20,000–25,000. Many researchers now emphasize the regulatory and non-coding parts of the genome, which bring the grand total into that broader range.

• The real take-home for nutrition-focused learning is not memorizing a precise total, but appreciating that the genome is bigger than a single line of code. It includes both the ingredients and the rules for using those ingredients. That layered complexity shapes how diets influence health over time.

From theory to practice in client conversations (the practical, non-exam-y part)

• Start with neutral questions: What foods feel energizing or heavy for you? How does caffeine affect your sleep? Do you notice dietary patterns that seem tightly linked to mood or energy?

• Tie in physiology, not just numbers: Explain how enzymes, transport mechanisms, and regulatory signals influence how meals are processed. Acknowledge that genetics is one piece of a larger puzzle that includes gut health, hormones, activity, sleep, and stress.

• Use plain language with positive framing: Instead of “your genes do this,” say “your body has certain natural tendencies that interact with your choices.” The goal is empowerment, not determinism.

• Encourage clients to focus on actionable steps: balanced meals, regular meal timing, adequate fiber, hydration, and consistent activity. If a client is curious about genetics, point them toward reliable educational resources and, when appropriate, professional genetic counseling or testing pathways. Always respect privacy and confidentiality.

What this means for your toolkit as a coach

• Knowledge anchors trust: You don’t need to be a geneticist, but knowing the basics helps you explain nutrition in a credible, relatable way.

• Personalization without pigeonholing: Genetics can hint at tendencies, but lifestyle data—food preferences, schedule, culture, and goals—often matters more for day-to-day choices.

• Resourceful curiosity: When clients ask questions about the genetic side of nutrition, you can acknowledge the nuance and offer to explore reputable sources together. Point them to trusted centers like the National Institutes of Health, the Genome.gov site, or peer-reviewed reviews that summarize what’s known about nutrigenomics without overpromising.

A quick note on sources you might encounter

If you’re curious to read more, consider these anchors:

• The distinction between protein-coding genes and the broader genome is well covered in introductory genetics texts and reputable online resources.

• ENCODE and related genome projects illuminate how much of the genome is about regulation, not just protein synthesis.

• Consumer-focused explanations of nutrigenomics discuss how gene-diet interactions can influence metabolism and health, always with caveats about variability and the limits of current knowledge.

A gentle wrap-up you can carry forward

Genetics adds color to our understanding of nutrition, not a single blueprint for every person. The number of genes isn’t a solitary statistic you memorize; it’s a doorway to appreciating how the body’s circuitry handles fuel, timing, and energy. The 35,000 figure you’ll hear in some places isn’t wrong as a broad, catch-all number, but it’s not the whole story. The important takeaway is this: there’s a vast, intricate network behind every meal, and recognizing that network can guide more nuanced, compassionate nutrition coaching.

If you’re weaving genetics into your studies or your client conversations, treat it as one thread in a larger tapestry. Pair it with behavior, environment, and goals. Keep the tone practical, clear, and hopeful. And when questions about the genome arise, meet them with curiosity rather than certainty—because in nutrition, as in life, the best paths emerge from balancing science with human experience.

For those who want to dig deeper, start with approachable primers on protein-coding genes versus non-coding regions, then explore how regulatory elements shape gene expression in response to diet and lifestyle. It’s a fascinating landscape, and understanding the basics can make your coaching feel both knowledgeable and genuinely helpful.