How to Lose Weight: The Truth About Fat Loss

In a world full of fad diets, celebrity-endorsed meal plans, and magic weight loss pills, it’s easy to feel overwhelmed or misled. But here’s the truth — fat loss isn’t complicated. In fact, the science is incredibly clear: to lose weight, you must be in a calorie deficit. That is the only truth about fat loss and how to lose weight.

No matter your body type, metabolism, or training background, this fundamental principle doesn’t change. What does vary is how you go about creating that deficit — and how sustainable and healthy your approach is.

In this article, we’ll break down the science of fat loss, explain the difference between calorie deficit and surplus, and help you understand how to structure your nutrition, training, and habits for long-term success.

This is your no-BS guide to losing weight — backed by evidence, not gimmicks.

What Does It Actually Mean to Be in a Calorie Deficit?

Let’s start with the basics.

Your body needs energy (calories) to function. This includes everything from keeping your heart beating and lungs breathing, to fuelling your workouts and digesting food. This total is called your Total Daily Energy Expenditure (TDEE). Find out your TDEE here.

When you eat fewer calories than your body needs, you enter a calorie deficit. In this state, your body begins to use stored fat for energy — leading to fat loss over time. For example if you consume 2,000 calories but burn 2,500 then you are in a 500 calorie deficit.

On the flip side, if you consistently consume more calories than you burn, you enter a calorie surplus. This is how people gain weight — not just fat, but potentially muscle too, depending on training and other factors.

This concept is known as the first law of thermodynamics, and it’s not a theory — it’s a law of physics. No diet, supplement, or training programme can bypass it.

How Much of a Calorie Deficit Do You Need?

A pound of body fat roughly equals 3,500 calories. So, to lose 0.5kg (just over a pound) per week, you need to create a deficit of around 500 calories per day. That could come from eating less, moving more, or a combination of both.

The sweet spot for most people is a moderate deficit of 15–25% below their maintenance calories. This allows for sustainable weight loss without extreme hunger, muscle loss, or fatigue.

As a rough example:

If your maintenance calories are 2,500, a deficit of 500–600 calories would put you at 1,900–2,000 per day.
Over a week, this should lead to 0.5–1kg of fat loss, which is considered a healthy and sustainable rate (NICE Guidelines).

Faster weight loss isn’t always better. It can lead to muscle loss, hormonal disruption, and binge-restrict cycles.

Methods for Creating a Calorie Deficit

There are two primary ways to create a deficit:

Reduce calorie intake through food — this is usually the easiest and most effective.
Increase calorie expenditure through physical activity — great for health and preserving lean mass, but harder to rely on alone.

The key is to combine both approaches in a way that suits your lifestyle. That might mean walking more, lifting weights a few times per week, and slightly reducing portion sizes.

There’s no single “best” diet for fat loss. Keto, low-carb, Mediterranean, vegan — they all work by putting you in a calorie deficit. The best diet is the one you can stick to consistently while still enjoying your life.

Where Does Exercise Fit In?

Exercise isn’t essential for weight loss — but it’s massively helpful.

Regular physical activity helps:

Burn extra calories
Preserve muscle mass while losing fat
Improve insulin sensitivity and metabolic health
Boost mood, energy, and sleep quality

The NHS recommends at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous activity per week, along with 2 or more strength sessions (NHS Physical Activity Guidelines).

A good rule of thumb: aim to move your body daily, lift weights 2–4 times per week, and find ways to stay active outside of structured workouts (e.g. walking, cycling, or even household chores).

But remember — it’s very hard to out-train a bad diet. One hour in the gym can’t undo 10 minutes at the drive-thru. A healthy body is created in the kitchen.

Why Nutrition Is the Most Important Factor

While exercise supports weight loss, nutrition drives it. You simply can’t lose fat consistently if you’re overeating — even if your food choices are “clean.”

To build a solid fat loss diet, focus on:

1. Protein Intake

Protein is critical during a calorie deficit. It helps preserve lean muscle, increases satiety, and has a higher thermic effect (meaning your body burns more calories digesting it).

Aim for 1.6–2.2 grams of protein per kilogram of body weight (Phillips & Van Loon, 2011). Good sources include lean meats, fish, eggs, dairy, legumes, and protein powders.

2. Calorie Awareness

You don’t need to count calories forever, but tracking intake for a few weeks can be eye-opening. Apps like MyFitnessPal, Cronometer, or MacroFactor can help you understand how much you’re really eating.

Once you’re familiar with portion sizes, you can shift to a more intuitive approach.

3. Whole Foods and Nutrient Density

Highly processed foods are often high in calories but low in satiety. Whole foods — think vegetables, fruits, lean proteins, whole grains, and healthy fats — provide more nutrients for fewer calories, keeping you full and energised. Generally, the more ingredients there are, the unhealthier it is! Stick to single-ingredient foods as much as practically possible.

That said, weight loss doesn’t mean you need to cut out all treats. An 80/20 balance between nutritious and enjoyable foods works well for most people. Healthy foods make up 80% of your diet, and 20% can be snacks and treats.

The Role of Habits, Mindset, and Lifestyle

Long-term fat loss isn’t about temporary restriction — it’s about changing habits. Crash diets might get short-term results, but they almost always lead to rebound weight gain.

Here’s what actually works:

Building meals around protein and plants
Eating slowly and mindfully
Managing stress and emotional triggers
Getting 7–9 hours of quality sleep
Creating a consistent (but flexible) routine
Being patient and realistic with your goals

Sleep, in particular, is crucial. As mentioned earlier, poor sleep can drive hunger, increase cravings, and disrupt hormones like cortisol and insulin — all of which make fat loss harder (Spiegel et al., 2004).

Common Myths About Weight Loss

“Carbs make you fat.” Nope. Eating too many calories makes you gain fat — not carbs. In fact, complex carbohydrates (like oats, sweet potatoes, and whole grains) can be part of a healthy, satisfying fat loss diet.

“You need to detox to lose fat.” Your liver and kidneys detox your body — no juice cleanse required. Save your money.

“You must eat six small meals a day.” Meal frequency doesn’t matter as much as total calorie intake. Some prefer three meals, others like intermittent fasting. Both can work.

“Fat loss must be miserable.” Not true. While there will be moments of discomfort, fat loss done right is sustainable, enjoyable, and empowering.

How Long Does It Take to See Results?

Healthy weight loss is around 0.5–1kg per week. Faster isn’t always better — and scale weight will fluctuate due to water, glycogen, hormones, and digestion.

Track progress using multiple tools:

Weekly weight averages
Progress photos
Waist measurements
Clothing fit
Energy, sleep, and mood

The key is consistency over time. As the saying goes: “It’s not about being perfect, it’s about being consistent.”

The Truth About Fat Loss: How to Lose Weight Sustainably and Keep It Off

Losing weight isn’t magic. It’s biology. And while the formula is simple — eat fewer calories than you burn — the execution takes effort, patience, and self-awareness.

The best approach isn’t the most extreme. It’s the one you can stick to, enjoy, and build into a lifestyle. Focus on whole foods, move your body regularly, get enough sleep, manage stress, and don’t panic if progress is slow. That’s how lasting change is made.

Forget quick fixes. Build something that lasts.