Does Dieting Cause Weight Gain?

This sounds ridiculous: diets are meant to cause weight loss, not weight gain!

The headlines you read do have an element of truth - a large percentage of people who lose weight via dieting (defined below) will regain some of, if not all, of the weight they are able to lose. On this fact alone, it becomes easy to compellingly argue that diets cause weight gain.

As usual, there is more to to story. Dieting does not cause weight gain, but weight is often gained after a successful weight loss phase. This is partly due non-adherence; having more weight to gain (the leaner you get, the easier weight gain becomes); and a few other factors that are outlined below.


Define Diet

Before we get too analytic, let's consider what a diet is:


Diet (noun)

the kinds of food that a person, animal, or community habitually eats.

a special course of food to which a person restricts themselves, either to lose weight or for medical reasons.


In this situation, we are talking about the second definition, whereby a recourse of food is used to reduce weight.

Of course you can lose weight by keeping food intake the same - and adding exercise - but I consider that the majority of successful weight loss is associated with decreased energy intake.

Now let's test the hypothesis that dieting causes weight gain.

Essentially, we are saying that if you restrict food intake you will gain weight. This is an oversimplification, but let's not even run with it: I am sure you will agree that consuming less energy will not cause weight gain.

If we look a little wider, we could consider the fact that dieting might lead to weight gain in the long run. By that I mean if someone successfully adheres a to energy-restricted nutrition protocol (diet) for a period of time, eventually progress will halt and they will plateau.

At this point, they can either add more exercise, or consume less food, but either way, they must maintain an energy deficit to continue losing weight.

They now required less energy for the same activities they did before. This can be known as their 'metabolic set point' having changed.

Not everyone wants to train like this.

Not everyone wants to train like this.

For many people who have successfully lost this weight, they are happy with the progress and are happy to maintain their loss of body fat, instead of chasing further loss. However, what often happens is that old habit begin to creep back in during this maintenance phase.

Without the motivation of scale weight decreasing, rapid progress in the gym, and enjoying the physical changes, it becomes harder to stick to the nutrition program (because you are no longer getting the benefits that were happening before; now it is just maintenance). People like rewards and progress, not maintenance.

This makes it easy to revert to old habits, and the weight can - not will - come back (from the energy surplus).

As you can see, dieting did not cause weight to be gained. Instead, it can be hard to maintain an energy balance/deficit, causing weight gain.


Correlation v Causation

If the majority of people who lose weight via dieting end up regaining that weight, is that not evidence that dieting causes weight gain?

No. This is a correlation, not causation.

There is a correlation between dieting and weight gain for a number of reasons.

  1. You have to diet in the first place to regain the weight. It seems obvious, but this is an underrated consideration. People who continue to gain weight without dietary intervention are not in any better position than those who lose and regain some, or even all, of it.
  2. After losing weight, less energy is expended than similar activity was before.
  3. It is harder to adhere to nutrition protocol (diet) once results slow. Law of diminishing returns. 

However, none of these are caused by dieting itself. In fact, if you successfully adhere to a well-planned diet you will lose weight!


Good Diets v Bad Diets

It's like Good Carbs V Bad Carbs - context is key.

It's like Good Carbs V Bad Carbs - context is key.

The more experienced I become, the less I think of diets or nutrition protocols as good or bad.

Quite frequently, small energy deficits and nutrition changes that are sustainable in the long term are favoured over larger energy deficits that deliver faster results.

While sustainability is important - moreso sustainable food habits and exericse than actual food intakes - not everyone gets their best results this way.

Let's consider two people who are 20kg overweight and wanting to make a change. 

Person number one creates a 25% energy deficit (upper end of the scale, but manageable) for 6 months and loses 20kg of weight. In the following 6 months, they ease off their deficit and gain 5kg (for a total weight loss of 15kg in 12 months).

Person number two creates a 15% energy deficit and loses 15kg over 6 months. In the following 6 months, they maintain their weight (for a total loss of 15kg in 12 months).

Both clients have essentially gotten to the same result, but you could argue the pros and cons of each system for the individual.

Person one might have gained weight after the program, but maybe they needed to be motivated by their early progress to stick to the system? If their progress had been slower, the might have stopped after only 2kg loss.

Likewise, person two might have found system one too extreme and been unable to stick to it, resulting in no loss.

Neither is necessarily better, they are just different. If we had assigned the opposite diets to the people, maybe they would neither have gotten results.

Consider that 3+3=6, but so does 2+4 and 3*2. The outcome is the same, but the methodologies used to get there are different. 

Once you go down the path of 'good or bad', 'x causes y' or 'just do this', the application to an individual becomes limited. 


The Real Questions

Is Dieting Bad?

No. An energy deficit is a necessity to lose body fat - you cannot achieve this any other way. If food intake is around, or slightly over, maintenance level, the addition of sufficient exercise can create this deficit and associated fat loss.

However, if exercise alone cannot create the deficit - be that for enjoyment or just a large deficit - dietary modifications must be made. There is no way around this, a deficit is essential!

Extreme energy restriction can lead to nutrient deficiencies or disordered eating, but a 15-25% deficit is not extreme.

For most people, the health benefits of weight loss will far exceed the short-term nutrient deficiencies. 

The insinuation that diets don't cause weight loss is ludicrous. However, headlines that grab your attention are the key to getting readers to quality information (ie. What to do After a 'F**k It' Day), so the intentions can still be good.

However, the danger comes from people who don't read the good content and just stick with the headline. They have 'evidence' diets do not work and look towards alternative answers for fat loss. I won't list these answers, but people who spruik gravity as causing arthritis - because gravity is a toxin - are the type of people you should ignore.


Does Dieting Cause Weight Gain?

No, dieting does not cause weight gain. However, an increased energy intake and/or decreased energy expenditure following a diet will cause weight gain.


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How to Prevent Weight Regain

The solution is simple (as always). Everyone needs to stick to an energy controlled diet that fits within the government guideline. Do this, exercise five times per week, and everything will be fine.

However, in the real world of long work hours, high-pressure jobs, raising a family, and Donald Trump, it becomes hard to do all of this. In these circumstances, a more individualised approach to creating a energy deficit might be required.

A time-poor executive might focus on reduce energy intake from food, by increasing the nutrient density of their food (more nutrients/kcal energy; fruit, vegetables, lean meats, etc) as this will up less time in their busy day.

A busy stay-at-home parent might find themselves cooking more energy dense foods, because this is what their children will eat (not like to eat, will eat). Creating a second menu is more stress than they need right now.

They might focus on increasing energy expenditure through physical activity, be that one or two 10-15 minute bodyweight interval workouts per day and/or getting the kids involved in a bike ride.

Finding the solution that fits your goals, experience and lifestyle remains the key. Any system will get results if it is adhered to, but not every system will be adhered to.

The reason for post-diet weight gain is no longer adhering to the system, which can be caused by a lack of motivation (no longer getting results) or a 'this is done' mentality.

Progression leads to motivation, which is an important consideration that should never be ignored. During the weight loss phase, the scale keeps moving down and it's easy to see a return on the time and effort into your program. During a maintenance phase, this ROI disappears (or decreases).

Strength continues to progress after weight is lost, providing long-term progress and motivation.

Strength continues to progress after weight is lost, providing long-term progress and motivation.

One of the reasons I promote resistance training during the weight loss phase is that it can provide an ongoing source of progress (and therefore motivation) during the maintenance phase.

Strength will likely improve as you move into a maintenance phase, due to the removal of an energy balance. This means that there is still an ROI on your program (strength increase) which makes adherence more likely.

The same benefits can come from steady-state training such as running and bike riding. However, one of the challenges I see with these clients is it is hard to vary things up (to make it harder).

People often run at the same time of day and have an allocated duration (say 30 mins at lunch time). The distance is then dicatated by the speed you can run (6min/km). This means that in 30 minutes, running at 6min/km, you will run 5km. You find a track and stick to it.

It can be hard to increase the speed, because then you burn out towards the end of the distance.

It can be hard to increase the distance at the same speed, because then it will take longer (and you have a time limit).

This can be avoided, but it is certainly a pitfall that steady-state lends itself too (relevant article: Can Running Make You Fat?).



Dieting does not cause weight gain, but many people who lose weight will regain some, if not all, of the weight lost. This is caused by non-adherence to the system that got results and associated energy surplus.

Individualised approaches to training and nutrition to create an energy deficit are important to create a system that delivers results and increases the likelihood of longer term adherence, via progression and ongoing motivation.