Why Most Diets Fail (And What Actually Works for Sustainable Fat Loss) By John Pierson – Personal Trainer, London.

TL;DR

Fat loss, weight loss, and working with a personal trainer in London shouldn't mean cutting out all your favourite foods. Most diets fail because they’re too restrictive to maintain. In this article, you'll learn why flexible dieting is a more realistic approach — and how to start using it to build long-term, sustainable results.

Have you ever lost weight, only to gain it all back?

You're not alone. Whether it's keto, paleo, or the 5:2, you've probably found a diet that worked — for a while. But eventually, life gets in the way. You're tired of eating like a monk. You’re on the Waterloo & City line, staring at your Tupperware of steak and cashew nuts, wondering how this became your life.

The Diet Trap

Here’s the reality:80% of people who lose weight regain it within five years.And most of them are following “successful” diets.

That’s not because people are lazy or weak-willed — it’s because most weight loss diets are too restrictive to sustain long-term.

They work while you're on them. But what happens when you're not?

That’s the diet trap. You lose weight, but you can’t keep going. So the weight comes back.

All Diets Are Restrictive. The Key Is How They Restrict You.

Every diet – even the flexible ones – involves some form of restriction. That’s unavoidable if fat loss is your goal.

The difference lies in how that restriction is applied. Some diets restrict:

• What you eat (e.g., no carbs)

• When you eat (e.g., intermittent fasting)

• How much you eat (e.g., calorie counting)

Most popular plans (keto, 5:2, Whole30) do at least two of these. And the more rigid the rules, the harder it is to live your actual life.

That’s where flexible dieting comes in.

What Is Flexible Dieting?

Flexible dieting isn’t a branded diet. It’s a strategy.

Instead of cutting out entire food groups or labelling foods as “bad,” it helps you make smart trade-offs by focusing on:

• Hitting calorie and protein targets

• Eating foods you enjoy and can stick with

• Making realistic adjustments based on your lifestyle

In other words, you can still eat out with friends, enjoy the occasional dessert, and live like a human being — without blowing your progress.

It’s not magic. But it’s doable. And that’s the point.

Fat Loss That Actually Sticks

Here’s the truth:The best diet isn’t the one that gets results the fastest.It’s the one you can stick to long enough that the habits become automatic.

That’s how you get long-term weight loss – not just weight loss, but fat loss that stays off.

When your diet becomes a lifestyle, the results follow without needing to think about it every hour of the day.

How to Start Flexible Dieting Today

If you want to give this a go, here are 3 steps to start immediately:

1. Work out your calorie & protein targets

• A rough starting point for fat loss:Body weight (kg) × 24 = daily caloriesBody weight (kg) × 2 = daily protein goal (grams)(This is a simplified guide — a personal trainer can help you fine-tune it.)

2. Track your intake

• Use an app like MyFitnessPal or MacrosFirst for 7 days. Don’t aim to be perfect — just build awareness.

3. Make trade-offs, not sacrifices

• Got a dinner out? Adjust earlier meals.

• Craving a dessert? Hit your protein and work it into your budget.

Final Thought: Your Diet Should Work For You, Not Against You

There’s no one-size-fits-all approach to fat loss. But if your current plan feels like a constant fight, it’s not the right fit.

If you're in London and want personal support applying this — or you’re tired of short-term wins that lead to long-term frustration — we can help.

At The Workout Network in the City of London, we help busy professionals build leaner, stronger bodies with sustainable strategies that actually stick.