How To Lose Weight and Keep It Off: The Science

Reviewed by: Erica An, APD, BNutr&Diet

Dietary guidelines have changed over the years as research becomes more accurate in determining what we should eat to attain optimal health and weight. The strongest evidence to date shows that calories matter, but focusing on food quality is an equally important part of preventing weight gain and helping you lose weight.

As a dietitian, I am often asked about the best methods of weight loss. With so many fad diets out there, it’s no wonder why so many are finding it totally confusing about the best way to lose weight and most importantly, keeping it off!!

The simple answer to this question is that there is no perfect weight loss method! There’s no magic pill or magic formula as we are all individuals with different needs and what might work well for some might not for someone else. In saying that, there’s one simple equation that determines whether you’ll lose or gain weight: how many calories you consume and how many calories you burn.

So let’s take a look at a few of the common diets out there to see how they work and if they are effective.

Paleo Diet

The Palaeolithic diet, Paleo diet, caveman diet, or stone-age diet is a modern fad diet requiring the sole or predominant consumption of foods presumed to have been the only foods available to or consumed by humans during the Palaeolithic era. It’s a diet based on whole, unprocessed foods like meat, seafood, eggs, veggies, fruits, potatoes, nuts, healthy fats and spices. It avoids all processed foods and ingredients, including sugar, bread, certain vegetable oils, trans fats and artificial sweeteners.

Being high in protein and low in carbohydrates, it helps to suppress appetite whilst lowering calories through the elimination of all processed foods and sugars. So essentially it provides some great philosophies around eating whole foods. However, it’s essentially not nutritionally complete with the absence of grain, legumes and dairy. So, getting enough fibre and calcium poses a big issue.


Low Carb Diets

Low carb diet fads diets have become widely used in recent years and appear attractive with great initial results. Consequently, the evidence behind their long term effectiveness is limited. There are various types of low carb diets that range in the amount of carbs they allow.

Initially they result in rapid weight loss and this is often why so many find them attractive. Weight loss will occur through a depletion of muscle glycogen and water loss. Glycogen is a form of glucose (energy) which is stored in muscles. Without carbs (or very low intake of carbs) it will lead to depleted glycogen stores. Also, because water is bound to glycogen, a large amount of your initial weight loss is in fact water.

Weight loss on low carbohydrate diets is also generally associating with; eating less energy-dense or processed food and higher protein intakes. This can help with appetite control and maintenance of muscle mass. However, in the medium and long term these diets do not seem to result in faster weight loss, or better maintenance of weight loss, than traditional energy restricted diets. There’s also the issue of sustainability and whether you can eat so restrictively long term and this is where it becomes an issue.


Ketogenic / Atkins diets

On a ketogenic diet, people eat a very small amount of carbohydrates, a moderate amount of protein and a large proportion of fat per day. This means that the body uses fat as its main source of fuel and breaks it down into ‘ketone bodies’ (or ‘ketones’) in a process called ketosis. Ketones are compounds your body naturally produces when too little external glucose is available.

People on a keto diet usually eat only 20–50g of carbs per day. As an example, 50g of carbohydrate is equivalent to 2 slices of bread and a banana. Because it’s very limiting, a large number of people tend to drop out of the diet, contributing to unhealthy, ‘yo-yo’ dieting behaviour.

Keto diets can also be high in unhealthy saturated fats, low in fibre and also low in some essential vitamins and minerals that we only tend to find in carbohydrate rich foods. Subsequently, this can lead to health issues such as constipation, fatigue, high cholesterol and osteoporosis.


Intermitted fasting

Intermittent fasting is a diet regimen that cycles between brief periods of fasting. This is with either no food or significant calorie reduction, and periods of unrestricted eating.

There is some evidence suggesting that Intermitted fasting can be effecting “re-booting” weight loss. Specifically, for those who have tried long term calorie restrictive diets with little effect. Intermittent fasting attempts to address this problem by cycling between a low calorie level for a brief time followed by normal eating, which may prevent these adaptations. However, research does not consistently show that intermittent fasting is superior to continuous low calorie diets for weight loss efficiency.


The important thing to note about all these diets is; one whether they are safe, two do they work and three (and most importantly) can you sustain them long term? In most cases, these diet fads are not sustainable long term. That’s where people fail as they get to a point where it’s no longer feasible or sustainable. They go back to their ‘old’ ways of eating as the diet itself has not taught them any easy or sustainable healthy eating practices.


So Which Will Help Me Lose Weight?

Is this all even more confusing? It’s hard not to be with so much conflicting information out there but it’s important to note that most of these diets have a few things in common which you can take away from it. They are calorie restricting. Which, as we all know is essential in losing weight, they restrict processed, sugary foods and promote consumption of whole foods. These are all great strategies that we need to adopt when wanting to lose weight and establish a healthy life. However, it’s the overall nutrition and long term sustainability that we need to focus. That’s what I feel we do so well here at 12WBT.

Another important factor to consider is the psychology around weight loss. A study published in the New England Journal of Medicine, 2009 compared the effectiveness of a range of different diets. It found that the more dietary counselling sessions participants received the better their weight loss results and the less weight they regained. This supports the idea that not only is what you eat important. But behavioural, psychological, and social factors are important for weight loss and long term weight maintenance as well.

So in conclusion, although all the above ‘diets’ can work to help you ‘lose’ weight the most important thing is to establish an eating style which is habitual or one that becomes a lifestyle change. If this is not established, the weight will usually be regained with resumption of previous habits.

If you’re after step-by-step guidance and professional support, 12WBT offers a range of programs based on diverse needs. Such as, losing that last five kilos or getting rid of post-pregnancy baby weight. Click here for more info.

Also Read: How I lost 20KG

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