Why do we feel tired more after 40, how to change it?

24 Feb

If you’re a woman in your 40s or beyond and you’ve noticed that your energy just isn’t what it used to be, you’re not imagining it. Every day I hear women say things like: “I wake up already tired,” “I hit an afternoon crash and feel like I just need to lay down” or “I feel exhausted even when I’ve slept many hours.”

There are several reasons this happens, but two of the biggest are hormonal changes and blood glucose (blood sugar) balance changes. And while both matter, blood glucose is often the hidden piece that makes the biggest difference to how you feel during the day.

The good news? Once you understand how your hormones and blood glucose work together, there are simple things you can do to support and boost your energy after 40.

Hormonal Changes After 40.

From your late 30s and into your 40s, many women begin the transition toward perimenopause. During this time, hormones such as oestrogen and progesterone in woman’s body start to change.

These changes can affect your daily energy in several ways:

Sleep may become lighter or more disrupted
Stress can become harder to get through
Mood and motivation may change
The body becomes more sensitive to blood sugar swings

Oestrogen actually influences how the body uses glucose from food to produce energy. As oestrogen levels change, the body may not regulate blood sugar as smoothly as before. This is one of the reasons many women notice energy dips, cravings, or brain fog in their 40s.

However, hormones are only part of the story.

The Bigger Energy Drain: Blood Glucose Swings.

One of the most common reasons many women feel tired during the day is unstable blood glucose.

When your blood glucose rises quickly and then drops, it’s harder for your body to control and can it can lead to:

Sudden feeling tired
Brain fog
Irritability
Sugar cravings
Afternoon energy crashes and feeling sleepy

This is especially common in women who are having meals heavy in refined carbohydrates (pastries, white bread, sugary snacks) without enough protein, fibre, or healthy fats.

Insulin And Blood Glucose.

Insulin is hormone produced by your pancreas. Insulin has very important function: move glucose into cells, where is converted into energy. After meals your blood glucose naturally rises, more insulin is produced, to get more glucose from the blood into cells. This important process happens in your body all th time. Is crucial to keep your daily energy levels stable and steady glucose balance, preventing energy crashes and blood sugar swings.

Women 40+ can experience changes in insulin sensitivity: the cells can become less sensitive to insulin, disrupting important glucose-energy balance in the body. This means that less glucose is being push into cells, less energy is being produced, more unused glucose stays in your blood and harder for your body to keep the stable blood sugar-energy balance, leading to feeling tired all the time, sugar cravings, brain fog.

In simple terms:
Your body still wants to keep blood sugar stable, but it becomes harder. Right daily habits and eating are very important to keep glucose-energy balance right .

When blood glucose is stable, energy level often improves.

What a Blood Sugar Crash Feels Like

Many women don’t realise their tiredness is connected to blood sugar because the symptoms can feel subtle at first.

You might notice:

Feeling tired about 1–3 hours after eating
Wanting coffee or sugar to “get going”
Energy dipping mid-morning or mid-afternoon
Feeling shaky or irritable when hungry
Craving carbs in the evening

These are common signs that blood glucose may be rising and falling too quickly.

Why This Matters More After 40?

As we get older, the body becomes a bit less forgiving of habits that used to “work fine.”

For example:

Skipping meals
Eating mostly carbs at breakfast
Long gaps between meals
Relying on caffeine to push through fatigue

In your 20s or 30s, your body might have coped well with these patterns. But when women reach 40, daily food habits can start to affect energy much more.

The solution to this often isn’t eating less or more — but eating differently to supporting stable energy throughout the day.

The Energy Formula Your Body Needs.

To maintain steady energy thorough the day, your body needs:

A steady glucose supply from food
Regular signals of nourishment (not long periods without food)

This is why the structure of your meals matters more than you might think.

Two Simple Ways to Boost your Energy Naturally after 40.

The good news is that you don’t need complicated meal routines. Small adjustments can make a big difference.

1. Build a Blood Sugar Friendly Breakfast.

Breakfast sets the tone for your energy all day.

If breakfast is mostly refined carbohydrates (plain toast, cereal, pastries), blood sugar often rises quickly and then drops — leading to a mid-morning crash.

A better breakfast option:

Protein
Fibre
Healthy fats

For example:

Eggs with vegetables and avocado
Greek yogurt with nuts and berries
Porridge with seeds and protein (like yogurt or nut butter)

This helps to keep your energy stable for longer and reducing fatigue.

Many women notice that just improving breakfast reduces cravings and fatigue significantly.

2. Don’t Wait Until You’re Exhausted to Eat.

Long gaps between meals can cause blood sugar to drop too low, which then triggers fatigue and cravings.

Instead, try:

Eating regular meals
Including protein at each meal
Avoiding relying on coffee instead of food to pick you up

Think of your body like a phone battery — if you only recharge when it’s at 1%, it struggles to keep up.

Small, balanced meals help maintain consistent energy levels.

The Role of Stress and Cortisol.

Another piece of the puzzle in feeling tired easier is stress.

After 40, many women admit their life gets more stressful. Juggling careers, family, aging parents, and life pressures. Stress triggers release of stress hormones, pushing blood glucose and energy production in the cells up. Chronic stress means cortisol is constantly high. This is not a good thing, is disrupting your blood glucose balance, wearing out cells by constant high energy demand, and contributing to insulin resistance and increased type 2 diabetes risk.

When cortisol is elevated: