Why Eating Less Food Doesn’t Always Mean Losing Weight

By Nick Nation, Perth Accredited Practising Dietitian and Certified Fertility Dietitian

If you’ve ever thought, “I’ll just eat less and the weight will fall off,” you’re not alone. On paper, it makes sense: fewer calories in = fewer kilos on the hips. Simple, right? Except… the human body is not a calculator—it’s more like a suspicious detective who doesn’t trust you and is constantly looking for ways to keep you alive (even if that means keeping a little extra around the middle).

As a Perth dietitian who sees this every week in clinic, I can tell you: eating less doesn’t always equal weight loss, and sometimes it can even backfire. We're not saying that calorie deficits don't work. It's more if the calorie deficit is accompanied by a nutrient deficit as well...and to stay out of a nutrient deficit, we really do need to eat regular well balanced meals.

Let’s break down why.

1. Your Body Isn’t Just Counting Calories, It’s Counting Nutrients

When you cut back too far, you’re not just reducing calories—you’re also cutting out important nutrients your body needs to actually function. Think about it: if you’re barely eating, where are your anti-inflammatory nutrients coming from? Vitamins, minerals, antioxidants, omega-3s—these are the team players that help keep inflammation in check, balance hormones, and support overall health.

Without them, your body is under extra stress. Inflammation can make it harder to lose weight, easier to store fat, and can leave you feeling like a zombie who just crawled out of bed…This is where working with a dietitian or nutritionist can be a game-changer—helping you eat enough to fuel your body, without starving it of the nutrients it needs.

2. Your Metabolism Learns to “Do More With Less”

Here’s the kicker: eat too little for too long, and your body thinks a famine has hit. The smart little detective in your brain sends a memo to your metabolism: “Slow down, team—we don’t know when food is coming back.”

So, your body burns fewer calories doing the exact same things. Walking the dog? Burns less. Sitting on the couch watching Netflix? Burns less. Even fidgeting (yes, that counts!) uses fewer calories. It’s like your body swaps out a roaring fireplace for one of those tiny tealight candles.

You’re eating less, but you’re also burning less. Not the win you were going for. This is something I explain often in my role as a Perth dietitian—your metabolism adapts, so simply “eating less” isn’t the long-term solution.

3. The Big Holiday/Family/Birthday Calorie Spike

Now let’s talk about the real world. Because life isn’t a permanent kale salad. Sooner or later, there’s a birthday, a family visit, or a holiday where the food is flowing. And after months of surviving on rabbit rations, your body sees the sudden calorie influx and goes, “YESSS! Let’s store every crumb—we don’t know when the famine will return!”

That’s why people often find themselves in the cycle of “eat less, lose a little, eat normally again, gain it all back (and then some).” It’s not because you’re weak or “bad” at dieting. It’s because your body has been trained to cling to calories like a toddler clutching their favorite toy.

So, What’s the Better Approach?

Instead of slashing calories into oblivion, aim for balance. Fuel your body with enough energy to keep your metabolism humming and include plenty of anti-inflammatory foods (think veggies, berries, nuts, olive oil, fish).

This not only keeps your body functioning at its best but also makes you less likely to rebound when the birthday cake comes out.

Because the truth is, weight management isn’t about eating less—it’s about eating smart, fueling well, and giving your body what it actually needs. And if you’re not sure where to start, reaching out to one of our Nutrition Nation dietitians is a good place to start. We can help you cut through the noise and create a plan that actually works for your lifestyle.

For more information about weight loss, we've listed 3 key habits to follow here