Is Cardio or Weight Training Better For Weight Loss?

When it comes to weight loss, one of the most common questions I hear is: “Are weights or cardio more effective?” It’s a great question, but the answer isn’t as simple as one or the other. Let’s dive into the details to find out why both play a role in achieving sustainable weight loss—especially for women over 35.

You Can’t Out-Train a Bad Diet (Or Even a Healthy One in a Surplus)

First things first, no matter how much you train, you can’t out-exercise a poor diet—or even a healthy diet that’s still in a caloric surplus. Weight loss is fundamentally about energy balance: you need to burn more calories than you consume. Even if you’re eating clean, if your intake exceeds your energy expenditure, you won’t lose weight.

Research from the American Journal of Clinical Nutrition highlights that dietary intake is the most significant factor for weight loss. One study found that exercise alone, without dietary changes, had minimal impact on long-term weight loss . That’s why the focus should always be on maintaining a slight caloric deficit through nutrition first and using exercise to complement your efforts.

Why Lifting Weights is Essential in a Caloric Deficit

When you’re in a caloric deficit, your body naturally seeks to conserve energy. And guess what? Muscle is “expensive” for the body to maintain because it requires calories to sustain. This means that when your body is low on energy, it prefers to shed muscle before fat because muscle is metabolically active.

This is where weight training comes in. By training with heavy weights, you signal to your body that it needs to hold onto that muscle mass. You’re essentially telling your body, “Hey, we still need this muscle—don’t let it go!” This helps preserve muscle mass, which is crucial not just for aesthetics but for long-term metabolism and overall health.

A study published in Obesity Reviews found that resistance training during a caloric deficit not only helps retain muscle but also enhances fat loss outcomes when compared to cardio alone . Another study in the Journal of Applied Physiology demonstrated that individuals who combine a calorie-restricted diet with weight training preserve significantly more muscle mass than those who rely on diet and cardio.

How Cardio Fits Into the Picture

Now, cardio has its place, but here’s the thing: it’s not the magic bullet for weight loss. Once you’re in a caloric deficit, adding cardio can help accelerate fat loss. However, for women 35+, there’s a crucial factor to consider—cortisol.

Why Cortisol Matters for Women 35+

High-intensity cardio and long-duration sessions can spike cortisol levels. And while cortisol is a necessary hormone, too much of it can lead to muscle breakdown, fat storage, and that “tired but wired” feeling. For busy women with careers, families, and a million things on their to-do lists, adding more cortisol into the mix can sabotage your results.

Research published in Psychoneuroendocrinology shows that excessive high-intensity exercise, particularly for women in their 30s and beyond, can lead to elevated cortisol levels, which hinder fat loss and increase the risk of muscle breakdown .

That’s why, for my clients who are 35+ and entering perimenopause or menopause, I recommend a more sustainable approach: Low intensity steady state cardio. This type of cardio—performed in what’s commonly referred to as the “fat-burning zone”—helps keep cortisol levels in check while still supporting fat loss.

While many people think of the fat-burning zone as a magic bullet, the real reason it works for women in this stage of life is because it minimizes stress on the body while still burning calories.

Train Smart: Heavy Weights + Low-Impact Cardio = Success

The goal is to retain as much muscle as possible while burning fat. Heavy lifting allows you to preserve muscle mass in a deficit, while low intensity steady state cardio helps chip away at fat without overloading your body with stress. Combine these two, and you’re setting yourself up for sustainable, long-term success.

A review in the Journal of Strength and Conditioning Research supports this by showing that combining strength training with moderate cardio leads to greater fat loss and muscle preservation than cardio alone .

So, if you’re anything like my clients, and as you get closer to 40, you’ve started blaming age for the extra body fat, the aching joints, and the fatigue, here’s the wake-up call:

It’s not age. It’s how you’ve been treating your body. But the good news is, it’s never too late to make a change—and it doesn’t have to mean high-intensity workouts that leave you wrecked.

The Bottom Line

At the end of the day, both weights and cardio have their place in a well-rounded fat loss plan. But if you want to preserve muscle, boost your metabolism, and achieve long-lasting results, heavy lifting should be your priority. Cardio can then be added as needed, focusing on methods that support your goals, not stress your body.

If you’re tired of the quick-fix approaches and are ready for a method that actually works—and lasts—let’s get to work. Because it’s your time to look better, feel better, and move better than you did in your 20s.

Ashley

Vegan Iron Physiques

[email protected]