The Best Diet for Weight Loss

Written by Tamara Willner
Medically reviewed by 

9 min read
Last updated June 2019

To lose weight, you need to eat fewer calories than you use up. The best diet for weight loss is the diet that lets you do that in a way that does not affect your quality of life! Calorie counting is very restrictive and unsustainable, so we need to explore other ways to keep a good energy balance for weight loss.

‘What should I eat to lose weight?’ is one of the most frequently asked questions. The answer is simple but often complicated by things like personal preferences, dietary requirements, and people’s perceptions of healthy eating.

Headlines don’t help – a tendency to sensationalise nutritional research in the news means we’re bombarded with seemingly conflicting advice.

Do carbs make you gain weight? Is saturated fat bad for you? Oh wait, is it healthy? What about eggs? Should you avoid any of these foods if you want to lose weight?

The best way to make a decision is to weigh up the evidence for different diets (and by diets here we merely mean the eating plan you chose, rather than a restrictive regimen!).

More energy out, less energy in

While this is in line with the old saying of ‘eat less, move more’, and this is generally true, it doesn’t necessarily mean calorie counting.

The best diet for losing fat is the one that enables you to consume less than you use up while being in line with your personal preference.

The important thing is finding a way of eating that suits you best and that you can stick to in the long term.

So many people have experienced failing a diet, the most common reason being that they didn’t have enough willpower. However, not being able to stick to a diet long term usually means that you didn’t fail the diet, but rather the diet failed you. If you can’t stick to it, then it’s probably just not the right one for your individual needs.

Key points:

  • The basic principle to achieve weight loss is less energy in and more energy out.
  • The key is to find a diet that suits your personal needs and allows that to happen.

What about calories?

While calorie counting is not generally a sustainable weight loss diet technique, total calorie intake impacts weight more than different macronutrient ratios (i.e. how much carbohydrate, fat, and protein you eat).

Many studies comparing diets with different ratios of carbohydrates, fats, and proteins showed that the total amount of calories was what determined weight loss.

One study kept participants in a ward throughout (to eliminate any opportunities to consume more than reported) and gave them either a low-carb or high-carb diet over 6 weeks. Both groups lost similar amounts of weight, and inches off their waist, after 6 weeks.

The same results were seen in a 12-week study, as well as a study that compared different amounts of fats and proteins while keeping carbohydrates the same. So, completely different diets all resulted in a similar amount of weight loss, which demonstrates that there is no one size fits all approach and the best diet is one that you can keep up long term.

Calorie counting is one way of estimating how much you’re taking in compared to how much you’re using up, and is endorsed by many famous diet clubs, such as Weight Watchers. However, it is by no means the only way. Focusing on eating balanced meals and being mindful of how much food you need to feel full is a much more effective technique in the long term. For some people, obsessing over the numbers is counterproductive and actually leads to eating more in the end.

What many calorie counters often ignore is that exercise burns energy, which will help put you in an energy deficit, and has a whole host of other health benefits! So, as well as focusing on a healthy diet, see if you can incorporate more exercise into your routine.

Key points:

  • Total calorie intake is a determining factor of weight loss.
  • It is possible to be mindful of intake without counting calories.

How do most weight loss diets work then?

The majority of popular weight loss diets, for example, the Atkins or Dukan diets, aim to reduce your overall energy intake. They do this by swapping carbohydrates for less calorie-dense foods (non-starchy vegetables such as peppers and broccoli).

The Atkins and Dukan diets are both high-fat, high-protein but low-carb. We digest both fats and proteins more slowly than carbs, which generally makes us feel fuller for longer. Advocates of this diet explain that you remain feeling satisfied and not hungry while still being able to reduce your overall energy intake.

These examples of weight loss diets are very much restrictive regimens, which is not realistically sustainable for most people. However, the rationale of reducing your overall intake, while still feeling satisfied is a great example of how to approach a sustainable weight loss diet.

Key points:

  • Most weight loss diets aim in some way to reduce your energy intake.
  • Rigorous diets that eliminate food groups are not sustainable in the long term.

Should I cut out carbs for weight loss?

Carbs have been demonised in the media recently. Although reducing the number of carbs you eat in favour of healthy fats and protein could help some people lose weight, it is by no means necessary to eliminate carbs.

People tend to shed what is known as ‘water weight’ when they eat fewer carbs. As your body uses up its glycogen stores, it releases water particles bound to glycogen, and you will appear to be losing significant amounts of weight quite quickly.

This is what’s usually happening when people go on a crash diet – and is also partly why the weight is so easy to put back on. It’s mostly just water! It is not the same as body fat loss.

The more extreme ketogenic (keto) diet – which eliminates carbohydrates almost entirely, and focuses on eating a lot of fats instead – deprives the body of its primary source of fuel, glucose. The body then creates new metabolic pathways and starts burning up fat (or more accurately, ketones produced from the breakdown of fats) for energy instead. This process is called ketosis.

This may sound ideal, but while a keto diet does burn fat, it’s quite challenging to follow effectively in the long term, as one slip up will take you out of ketosis temporarily.

Overall, it seems that a lower-carb diet, but not a carb-free diet, is probably the most effective way to lose weight and keep it off. A study comparing the weight loss over 2 years between low-fat, low-carb, and Mediterranean diets demonstrated that all diets produced short term weight loss, with low-carb producing the most. At the 2 year mark, the low-carb group had maintained weight loss significantly more than the low-fat group.

Graph depicting weight loss over 2 years for a low-fat, low-carb and Mediterranean diets.

Here is some inspiration on how to eat low-carb, complete with recipes, easy swaps, and ideas.

Key points:

  • It is not necessary to eliminate carbs from your diet to achieve weight loss.
  • Reducing carbs, in favour of healthy fats and protein can be an excellent way to reduce your overall energy intake while remaining satisfied.

What’s the best diet for people with type 2 diabetes?

The evidence isn’t too different for people living with insulin resistance or type 2 diabetes. When focusing purely on weight loss, it is still about reducing your overall intake, rather than adjusting the ratios of protein, fat, and carbs. However, different macronutrient ratios seem to have other metabolic advantages.

Some evidence showed that women lost more fat, especially belly fat, on a high-protein diet compared to a low-protein diet, while another study concluded higher protein meant women lost less muscle when losing weight. Preserving muscle can aid weight loss, as having muscle increases your resting metabolic rate (how much energy your body burns at rest), which in turn helps to improve your energy balance.

Those living with type 2 diabetes need to control their blood sugar levels, as their bodies do not respond to insulin which controls this in healthy individuals.

The lower carb diet in the previously mentioned 6-week study appeared to have a more favourable impact on blood sugar levels than the higher carb diet, which may make it a better option for someone at risk of type 2 diabetes. But for weight loss alone, it was the overall energy intake that mattered, and in any case, weight loss is associated with better glycaemic control regardless.

Key points:

  • For the aim of weight loss, the evidence is similar for individuals living with type 2 diabetes than it is for healthy individuals.
  • As blood sugar levels are a focus in type 2 diabetes, low-carb diets can help prevent spikes in blood sugar compared to other diets.

Do fasting weight loss diets work?

As we have discussed, the important thing for weight loss is reducing overall energy intake, and fasting can help some people achieve that. Some people work well with the rules and structure of fasting diets.

Many fasting diets claim to aid weight loss. None of the fasting diets, including time-restricted feeding and intermittent fasting, limit your carbohydrate intake. They do, however, reduce the time you spend eating, resulting in reduced energy intake for a lot of people.

Fasting diets are certainly not for everyone though, and the evidence is mixed. Some people will experience adverse side effects from not eating or eating very little for periods, while others may compensate elsewhere for skipped meals and end up eating more overall. As with all the other diets mentioned, it’s about whether that way of eating suits you.

Key points:

  • Fasting diets can help with weight loss but are by no means a requirement.
  • The majority of fasting diets work by providing a structure to limit energy intake.
  • More research needs to be done to confirm any benefits of fasting diets.

Fail-safe guidelines for any weight loss diet

Although many different diets can help with weight loss, some tips can be incorporated in all of them:

  • Avoid ultra-processed foods, such as biscuits, cakes and soft drinks.
  • Cut down on sugar.
  • Limit fruit juice and alcohol.
  • Build your meals around proteins (e.g. meat and pulses), healthy fats (e.g. olive oil and avocado) and non-starchy vegetables (e.g. peppers and courgette) rather than refined carbohydrates (e.g. white pasta).
  • Making a meal plan at the beginning of each week will help you stick to the diet you have chosen.
  • When you do eat carbs, opt for whole grain versions, for example, brown rice over white rice.
  • Move your body as much as possible. If you’re using up more energy than you’re taking in, you will most likely lose weight.
  • Try to practise mindful eating and eat free from distractions (i.e. not in front of the TV).

Why we should play the long game

The problem with several diets is maintenance. As we have mentioned, many people may find them too restrictive, and ultimately unsustainable in the long term.

Evidence shows that most people put the weight back on and then some when they ‘fall off the wagon’. Re-gaining weight can lead to restriction and create a cycle of bingeing and restraint, which may lead to yo-yo dieting and weight gain.

Maybe you’re the sort of person who can happily count calories and stick to a certain amount without too much trouble (physical or psychological). You may prefer not to count calories, and opt for a diet that lets you eat as much as you like of certain foods because then you don’t have the mental barrier of restriction, and your body will self-regulate when you eat enough fats or protein.

You might be perfectly happy never to eat carbohydrates again, just as others may want to follow a vegetarian or a vegan diet.

The important thing is to find a way of eating that means you are using up more energy that you are taking in without compromising your health, your energy or your happiness. Only you can work out what the best lifestyle change is for you!

Take home message

  • Highly restrictive diets may work in the short term but will ultimately fail, and weight loss will not be maintained.
  • The bottom line is you should aim to use up more energy than you take in, and there are many different ways to achieve this.
  • Most weight loss diets work by reducing your overall energy intake in some way.
  • It is not necessary to eliminate carbs from your diet to lose weight.
  • Reducing carbs, in place of healthy fats and protein, may help you improve your energy balance while still feeling satisfied.
  • Those living with type 2 diabetes might experience other benefits from a low-carb diet, such as blood glucose regulation.
  • Fasting diets help some people, by providing a structure and set of rules that are easy to follow but are not for everyone.
  • The best diet is the one that you can stick to for the long term!
Like what you read here?

Take our health quiz today and see whether the 12-week OurPath programme can help you to change your lifestyle.