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How to Lose Weight Naturally: The Science Behind Losing Weight

“Fat reduction needs a calorie deficit.”

You’ve heard it everywhere – and technically, it’s true. To lose fat, your body must use more energy than it takes in. But that’s only one part of the story.

In practice, many people reduce their calories for weeks – sometimes drastically – yet see little or no change in body fat. Others can lose weight quickly at first, only to plateau or lose mainly muscle, instead of fat.

So, if calories matter, why doesn’t the math always work?

To understand how to lose weight naturally, we need to take a deeper look at the science behind losing weight, and how your body actually responds to changes in diet, hormones, and energy balance.

To lose weight naturally, you need a steady (not extreme) calorie deficit supported by quality sleep, hormones, and protein intake. Research shows muscle prevention, nutrient density, and stress control are all key parts of the science behind losing weight effectively – and keeping it off.

Read on to discover how to lose weight naturally, the real science behind fat loss that fad diets don’t tell you, and how to create an environment where your body can burn fat effectively and sustainably.

The Truth About Calorie Deficits

By definition, a calorie deficit means that your body exerts more energy than it consumes. In this state, it draws on stored energy from glycogen, fat, or, if pushed too far, muscle, bones, and organs – to make up the shortfall.

That’s the foundation of fat loss, but it’s also where the science of losing weight gets more complicated. Your energy balance isn’t an exact number – it’s a fluctuating equation that’s influenced by many variables.

Online calorie calculators and fitness trackers offer a guide, but it’s not a guarantee. Studies have shown a difference between actual and calculated calorie burn in about 30% of cases.

What Does Your Calorie Needs Depend On?

Your true energy needs shift daily, and depend on:

Activity level
Total muscle mass
Sleep quality
Physical and mental stress levels
Basal Metabolic Rate (the minimum number of calories your body needs to perform basic life-sustaining functions, such as breathing, circulation, and cell repair, while at rest)
NEAT (Non-Exercise Activity Thermogenesis)
Thyroid function and hormones

So while calorie balance matters, understanding how to lose weight naturally means recognising that your body is dynamic, not mechanical.

Why Your Body Isn’t a Calculator

In theory, eating less equals losing weight. In reality, your body doesn’t behave like a simple math equation – it’s an adaptive system that’s designed for survival.

When calorie intake drops sharply, your body makes changes to compensate for the lack of incoming energy by saving energy:

Basic metabolic rate slows down
Thyroid hormone levels (T3 and T4) drop
Non-exercise movement decreases
Appetite and cravings increase

These are subconscious survival mechanisms. The body isn’t aware that you’re dieting, even if your conscious brain is – it only senses scarcity and reacts.

Over time, this “metabolic adaptation” makes fat loss slower, harder, and more frustrating. Extreme calorie restriction can even cause the body to resist fat breakdown entirely. Instead of burning fat, it clings to it, prioritising survival over aesthetics.

That’s why the key to losing weight naturally is balance, not extremes. So, how do you find this balance?

Hormonal Regulation: The Invisible Weight Loss Barrier

Hormones are the gatekeepers of energy use – deciding whether to store or release fat. Their most important roles include:

Leptin: Signals energy sufficiency to the brain. Low levels (from under-eating) tell your body to conserve energy.
Insulin: Regulates blood sugar and fat storage. Chronic stress or poor sleep can increase insulin resistance, making fat loss harder.
Cortisol: The “stress hormone”. Constantly elevated, it encourages belly fat storage and impairs recovery.
Thyroid Hormones (T3 and T4): Control metabolic rate. Dieting too aggressively can suppress them, lowering overall energy expenditure.

The science behind losing weight shows that hormonal balance is essential – not just calorie reduction.

Mitochondrial Function: Your Fat-Burning Engine

Fat loss depends on the mitochondria, which are the tiny “power plants” in your cells that convert stored fat into usable energy. If mitochondrial function is impaired due to stress, inactivity, or nutrient deficiency, fat burning slows down even if you’re in a deficit.

Micronutrients like magnesium, B vitamins, and iron are crucial for energy metabolism. That’s why it’s important to prioritise nutrient-dense foods and high-quality protein sources.

At Human Performance Hub, we provide Informed Sport certified Bone Broth Protein Powder that is rich in amino acids and collagen, supporting mitochondrial health, tissue repair, and gut function – vital for natural, consistent progress. Read our guide on how bone broth can help you lose weight to find out more.

Chronic Dieting & Metabolic Adaptation

When the body experiences long-term restriction, it adapts by lowering its baseline energy needs – which is a survival mechanism known as metabolic adaptation.

Common symptoms can include:

Fatigue and low motivation
Stubborn body fat that won’t shift
Reduced exercise performance

The solution to this lies in strategic nutrition, not further restriction. Maintain a steady protein intake (to preserve muscle) and strength train regularly to ensure that your body continues to use energy efficiently. Natural proteins like our HPH Bone Broth Protein Powder can be great for maintaining lean muscle mass and recovery during calorie restriction.

4. Female Metabolism & The Menstrual Cycle

Women’s metabolism naturally fluctuates across the menstrual cycle. During the luteal phase, calorie needs rise while insulin sensitivity drops. This can lead to water retention or slower visible progress – even when fat loss is occurring.

Cycle-aware training and nutrition are crucial when learning how to lose weight naturally. Adjusting protein and micronutrient intake throughout the month helps to sustain energy, mood, and progress.

5. Inflammation, Stress, & Fat Loss Resistance

Chronic stress can trigger inflammation and disrupt hormonal balance. High cortisol levels signal your body to conserve energy and store fat – especially around the midsection.

Inflammation from poor sleep, overtraining, or an unbalanced diet can also hinder fat metabolism.

Bone broth naturally contains glycine, an amino acid that supports relaxation, reduces inflammation, and promotes restorative sleep – all key factors in the science behind losing weight sustainably.

6. The Power of Protein for Natural Fat Loss

Protein is essential in any natural fat loss plan. It helps to:

Preserve lean muscle mass
Increases fullness and reduces cravings
Boosts calorie burn through thermogenesis

HPH Bone Broth Protein provides a clean, collagen-rich source of protein that supports gut health, muscle recovery, and hormonal balance – all vital parts of the science behind losing weight naturally.

7. Micronutrients: The Overlooked Fat-Loss Factor

Micronutrients like vitamin C, magnesium, and B vitamins play crucial roles in metabolism. When calorie intake drops, micronutrient intake often falls too – reducing metabolic efficiency.

The lose weight naturally, ensure your diet includes whole, nutrient-dense foods or consider supportive supplementation.

8. Sleep, Recovery, and Regeneration

Poor sleep disrupts hunger hormones – increasing ghrelin and reducing leptin – while raising cortisol levels. This hormonal shift increases appetite and decreases fat oxidation.

Studies show that those who sleep less lose more muscle than fat. Even in identical calorie deficits.

Quality sleep enhances recovery, hormone balance, and metabolic health – the foundation for losing weight naturally. Bone broth protein, rich in glycine, can support deeper, more restorative sleep and faster recovery. Find out more in our guide on bone broth and sleep.

Support Your Natural Weight Loss with HPH

At Human Performance Hub, we believe in supporting the body, not fighting against it. Our PaleoBeef Bone Broth Protein Powder offers a collagen-rich, gut-friendly source of protein – helping you stay strong, nourished, and energised as you lose weight naturally.

Clean ingredients, backed by science, and designed for results.

Shop HPH Bone Broth Protein today and give your body the support it needs to perform and transform – naturally.

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October 20, 2025/by hphstore

Ask the coach a question, News from our Founder, Resources

Q&A By Roan – Fat Loss This Summer!

This month, we look at some body fat-burning strategies and health-supporting minerals to help you improve your fat loss this summer.

As discussed in many articles, fat loss is not a quick fix. Using the right supplements along a fitness routine can improve your training and increase fat loss while building endurance and becoming stronger.

July 13, 2022/by hphstore

Resources, Supplementation

Supplementation – What you need to know about Curcumin

“Spices, the friend of physicians and the pride of cooks”

Charlemagne – 8th Century King and Conqueror

September 14, 2020/by hphstore

Resources, Training & Performance

Training – The Lower and Upper Body Split

“The rule is: the basics are the basics, and you can not beat the basics!”

Charles Poliquin 5th March 1961 – 26th September 2018

August 31, 2020/by mattroanadmin

Resources, Supplementation

Supplementation: The benefits of L-Carnitine

Carnitine was first found in animal meats in the early 1900s. Over the course of the 19th century it was researched more and more where it was found that L Carnitine existed across all animal and plant tissues. In the 1980s, L Carnitine was known as a popular supplement with numerous books being written all about it. It continues to be widely used today, but its benefits are not as well known as they should be.

So, what are the benefits of L Carnitine? The main benefits of L Carnitine supplements are weight loss, energy production and healthy brain function. Numerous studies have shown L Carnitine to be effective in weight loss, whereas another form of Carnitine, ALCAR is thought to be effective in promoting brain function.

Read on to learn more about Carnitine, its different forms and how consuming supplements can benefit the body.

What Does L Carnitine Do? What is it?

L Carnitine is a combination of 2 amino acids; Lysine and Methionine. Together they create a single compound. This compound is mostly stored in the muscles (around 95%), whilst the remainder is stored in the liver and blood.

As a supplement, L Carnitine is known for two primary benefits; fat loss and brain function. It works by transporting fatty acids into the mitochondria cells. These cells act as engines, burning fats to create usable energy.

But, there are different forms of Carnitine. Be sure to take the correct supplement to receive your desired results.

What’s the Difference Between L Carnitine and ALCAR?

We don’t want this to turn into a chemistry lesson, but it is important to distinguish between the two main forms of Carnitine, namely L Carnitine and Acetyl-L Carnitine (abbreviated as ALCAR).

The different chemistry of carnitine means it has a different effect on the body and operates differently. In terms of function, these 2 mains forms can be distinguished:

L Carnitine – known to be good for fat loss and exercise performance.
ALCAR – known to be beneficial for brain and cognitive health.

Quite simply, ALCAR means that there is an acetyl group. This is where 2 carbons, 3 hydrogens and 1 oxygen have been thrown together onto Carnitine. Think of it as a Lego structure, you have 2 red bricks, 3 yellow bricks and 1 green added onto a central piece. It is this difference which changes the function of ALCAR.

Top L Carnitine Benefits

Fat Loss

Most of the early research of Carnitine was done on energy production and fat loss with L Carnitine. There is a general consensus that it has a good effect on this. A good way to illustrate how L-carnitine works is to think of a power plant.

In your body, you have mitochondria in almost all of your cells. The mitochondria are the furnaces using fuel for energy but to produce energy you need fuel. L Carnitine is the vehicle which delivers fuel to the powerhouse.

More specifically, L Carnitine brings fatty acids to the mitochondria so that the mitochondria can use them for energy production. As such, it can be useful to consume this supplement quite early on in your fat loss journey.

For this same reason, it has been used to good effect for exercise performance. Particularly endurance exercise which is heavily reliant on fat as fuel for the muscular work performed. By getting fats to the mitochondria more effectively, the energy production is more efficient as a result.

Brain Support

We’ve already discovered that using L Carnitine is great in the early stages for fat loss and exercise performance. But in the long term, there are other great benefits for your brain health and support.

Our daily lives are more than ever characterised by stress, inflammation and toxins, which means the cells of our body can be damaged and poorly-functioning. Thus, we need to support our bodies. In the context of Carnitine, we provide support for our brains!

We know that L Carnitine is good for energy supply, and we know that brain tissue and performance can suffer from lack of energy resources. However, L Carnitine struggles to get into the brain unless it is in the form of Acetyl-L-carnitine (ALCAR).

The brain has, in effect, a filter which means only certain substances in the blood can get through to the brain cells. This is a built-in protective system for the brain to prevent just anything getting in. ALCAR is able to pass this filter and exert a positive influence on the brain. In fact, ALCAR has several lines of decent research supporting its use for neurological health, whether that be with dementia, Alzheimer’s or cognitive decline in ageing.

Acetyl-L Carnitine has several influences in the brain which mean it is protective. As mentioned previously, energy supply is important for brain tissue and ALCAR is a great form of carnitine since it is actually able to get to the brain to supply energy.

ALCAR also has other ‘neuroprotective’ effects not just through energy supply. It is an antioxidant which helps to prevent free radicals (and toxins) from causing damage to brain cells. It also fortifies the mitochondria’s defences.

Internal Communications

Neurotransmitters are like the brain’s accelerator and brake pedals. They send messages between the cells of the brain where they either speed up, slow down, or modulate activity of the brain. This can affect your focus, alertness and wakefulness.

Of the 7 major neurotransmitters, Acetylcholine was the first to be discovered and is the one which we will briefly look at here. Since Acetyl-L Carnitine is made up of an ‘acetyl’ group attached to carnitine, it is able to provide acetyl groups to make the acetyl-part of Acetylcholine. This is important for improving alertness, memory and focus.

Acetylcholine irregularities have been linked with Alzheimer’s, showing the importance of this neurotransmitter for brain function .

When to Take L Carnitine

It is best to take a direct concentrated form of Carnitine. Many supplements contain it but they also contain numerous other ingredients and so this can lessen the effectiveness.

In scientific literature, the doses vary from 0.5g to 4g. From whatever dose you start at, it would be a good idea to titrate up. For example, start at a moderate dose (e.g 1g per day) and build up depending on how you respond to it.

In terms of when to use it, it is probably most optimal to take earlier in the day and before exercise. This way, you get the benefits at the right time. For example: