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Popular Weight Loss Diets: A Review of the Science

A review by Freire (2020) has examined the evidence for the most popular weight loss diets. Low carb, keto, paleo, gluten free, Mediterranean, intermittent fasting, you name it. What was the verdict?

There is not one magic weight loss diet that works for everyone. Are you surprised?

We are all unique with different biochemistry, different genes, different likes and dislikes and different reasons for why we put those unwanted kilos on in the first place. So why would we expect the same one diet to work for everyone?

I’m still waiting for my wish to come true… one magic weight loss diet (hello!?)

What does the science say?

comparison categories of popular weight loss diets and factors for success
The three main categories of weight loss diets and factors needed for success

When it comes to weight loss, there are basically three categories of diets out there:

  1. Manipulation of macronutrients (protein, fat, carbohydrates)
  2. Manipulation of timing (eating only within certain times e.g. 8am-4pm, or fasting on certain days of the week)
  3. Restriction of specific foods or food groups (plant-based, Mediterranean, gluten free, Paleo).

Below is a graph that shows the breakdown of protein, fat and carbohydrates of popular weight loss diets. As you can see, they all recommend a similar amount of protein (20-30%) but the variability lies with the recommended amount of fat (10-70%) vs carbohydrate (10-70%). That’s alot of variability!

graph macronutrient breakdown of popular diets
Macronutrient breakdown of popular diets

The next table below highlights the food groups that are included and excluded in popular weight loss diets. Again, all the diets agree that you should restrict refined grains and sugar, but it starts to get confusing when it comes to wholegrains, legumes, dairy, starchy fruit, starchy vegetables and animal-based products. I can definitely see why everybody is so confused about what to eat!

table foods included and excluded in popular diets
Foods included and excluded in popular diets

In summary, there were a few take-home messages from this review:

In the short term, diets that resulted in faster weight loss were generally lower in carbohydrates OR fat, lower in overall energy (calories), and may include some type of fasting (e.g. eating only within a certain window of time each day).

The issue however is that these strategies can be difficult to implement long term, especially when wanting to eat out in social situations, and can result in unwanted side effects such as constipation and headaches. They are also not suitable for certain populations, including women who are pregnant or breastfeeding. Careful monitoring by a qualified health care practitioner is recommended.

In the long-term, diets that focus on nutrient-dense high quality whole-foods, such as the Mediterranean diet, are most likely to result in sustainable weight loss and positive health outcomes.

Success also relies on adherence (which means choosing a way of eating and then being able to stick to it long-term).

What does this mean for you?

First of all, take a deep breath and know that losing weight is do-able when you bring it back to basics.

Eating real whole-foods, especially plenty of vegetables, good quality protein, and adequate water, getting enough sleep, moving your body, and managing stress, will always be the foundation. Your body wants to function at its best and we just need to work out what this looks like for you to help it along.

Book in a consult with a qualified nutritionist, like myself, who can help you pinpoint the dietary and lifestyle changes that will work best for you. Remember, everybody is an individual and the “how” and “why” of your journey is unique to you.

I’ll help you reflect on what, when, where and how much you are eating. Together we will personalise a dietary plan based on your age, gender, likes and dislikes, sleep routine, stress levels, physical activity, and other factors such as diagnosed health conditions.

A great starting point is my “Achieving Your Healthy Weight” package which is based on the Shake It Practitioner Weight Management Program. It is a step by step evidence based weight loss program that implements many of the strategies outlined in this scientific review.

You will be supported to implement changes over time so that your weight loss is gradual and sustainable. You will learn to identify what factors most likely contributed to your weight gain in the first place so you can take control of your current and future health. The long-term goal is to eat real food with confidence and to understand what you and your body need.

I’ve successfully lost 30kg and maintained this weight loss for many years now. I understand the ups and downs along the journey and can keep you motivated and accountable. Life is too short to be unhappy about your weight and to not feel your best. Let’s work together to find what works for you (remember we are all pretty much unicorns). Once you work this out, maintaining a healthy weight and preparing and eating meals becomes intuitive. You will know what to do and can focus on enjoying life.

Get in touch if you want to know more or have any questions.

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