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Weight Loss Programmes

Noom® vs Slimming World®

Tamara Willner
Written by

Tamara Willner

Medically reviewed by

Fiona Moncrieff

9 min read
Last updated May 2024

Weight loss programmes can provide a helpful structure for your health journey when you feel out of control with unhealthy habits.

They can also be a great way to join individuals going on the same journey, which can be incredibly motivating.

Everyone is different, and there’s no one-size-fits-all approach to choosing a weight loss programme.

It ultimately depends on what suits your individual needs and what fits into your lifestyle.

Regarding losing weight, some people want rigid rules and a quick fix, whereas others like more flexibility and a long-term lifestyle change.

To save you tiresome research and help to answer some crucial questions, this guide compares two popular weight loss programmes, Noom® and Slimming World® (SW).

Noom is an online app-based programme, whereas you can choose between online and face-to-face plans with Slimming World.

Comparisons to the Second Nature programme are included. Second Nature is a 3-month online programme that helps you to lose weight and make sustainable lifestyle changes.

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Noom may just be another strict diet

Despite Noom’s advertising as a sustainable weight loss solution and their use of behavioural science, their approach to nutrition mimics many of the restrictive dieting approaches also seen in Slimming World.

Dietitian and eating disorder expert Christine Byrne wrote a review on Noom for Outside magazine in 2021 and quoted:

“Don’t Be Fooled, Noom Is Just Another Diet.

The popular app promises weight loss without dieting. Then it proposes restrictive eating habits.

…behind Noom’s popularity and slick “no dieting needed” marketing, it’s really just another diet. The app is essentially a calorie tracker supplemented by lessons on behavior change and a personal coach who messages you. Many nutrition and mental health experts have warned that the way Noom presents itself is misleading.

Calorie counting on Noom

On Noom, you’re assigned a ‘personal’ calorie target. However, it seems that everyone is assigned a 1200-calorie target, no matter what information you put into the Noom quiz.

Like Weight Watchers and Slimming World, the Noom diet also has a food ranking system to inform you what foods are ‘good’ and ‘bad’. They use a traffic light system based on food’s energy density and nutrient availability.

Energy-dense foods (such as cheese) are labelled red foods, and low-energy-dense foods (such as veggies) are labelled green foods.

Strict calorie restriction risks putting your body into what’s known as ‘metabolic adaptation’. This is essentially a starvation response by your body when energy intake is very low.

This triggers a cascade of events designed to encourage you to eat more and continue to store fat. You might feel lethargic and hungry, and your mood might also experience a dip.

Slimming World uses a similar approach

Slimming World’s advice breaks down foods into “syns” and “free” foods. The syn foods are given a score on how bad they are; for example, a small chocolate bar is 5.5 syns, and an Oreo Thin is 1.5 syns per biscuit.

Their diet plan’s free foods include vegetables and oily fish, and you’re encouraged to enjoy these freely.

The word syn used in Slimming World is taken from sin in the English language and is defined as:

Any act regarded as such a transgression, especially a willful or deliberate violation of some religious or moral principle.

Effectively, Slimming World’s weight loss plan is passing judgment on your eating habits. By eating chocolate, you’re sinning, a deliberate violation of your moral principles.

This approach to food leads to the vicious cycle of guilt, shame, and overeating that’s common in strict diets and plays into what’s known as the “white bear effect” in psychology.

When you try to avoid thinking about something, it becomes more accessible in your mind.

Take food, for example; when you say, “chocolate is a syn, I can’t eat it”, you’ll think about chocolate more, your cravings for it will increase, and you’re more likely to overeat it.

This sounds counterintuitive, but this is human psychology; it’s complex and often doesn’t work in the way that best supports our health.

Ironically, to be able to manage your food choices, you need to allow yourself to consume all foods within a healthy diet. You’ll then find you’ll eat more healthily because you want to, not because you have to.

Because of the starvation response to strict dieting and our understanding of behavioural psychology, Second Nature has taken a different approach – one where you determine what level of intake works for you.

Surprisingly, it can lead to more weight loss in the long term.

Second Nature’s approach: Indulgent but supports weight loss 

In 2022, the NHS published data in the British Medical Journal from the National Weight Management and Diabetes Prevention programme, where five providers delivered weight loss services in the UK.

The results showed that after 12 months, Second Nature was more than twice as effective as the four other providers. Currently, Noom has no published long-term data to support its approach.

Our approach has also been shown to support people improve their blood sugar levels and blood pressure and live healthier lifestyles.

How does Second Nature’s approach work?

We approach nutrition and healthy eating differently. We don’t count calories, track macros, weigh food, or assign strict targets on your intake. No foods are off-limits on Second Nature.

We provide you with evidence-based guidance on a balanced diet and what healthy foods look like and teach you to understand what your physical and emotional drivers for eating are to reach your weight loss goals.

We also provide tools, such as our hunger scale and mindful eating techniques, that help you tune into your physical hunger cues and manage your food choices.

Alongside this, we help you build healthy habits, like increasing your physical activity and managing stress, that you can enjoy for a lifetime to help you maintain a healthy weight.

Our feedback inbox is filled with people like Jo, who lost over eight stone to achieve a healthy body weight on Second Nature after following our nutrition guidelines and receiving the support of our app and health coaches.

The difference is that members of Second Nature learn to love food again. They’re no longer restricted. They’re liberated.

If you’d like to join over 150,000 others who’ve joined Second Nature, lost weight and kept it off, then click here to take our health quiz.

Otherwise, keep reading as we look at other key differences and similarities between Second Nature and the Noom programme.

Trustpilot score

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SW Noom Second Nature
Star rating 3 stars 4 stars 5 stars
Score 2.4 / 5
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4.3 / 5
read reviews
4.8 / 5
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Signing up

SW Noom Second Nature
Moneyback guarantee Full refund (apart from $1 admin fee) if cancelled within 14 days. After this point, any charges non-refundable. Full refund if cancelled within 14 days. After this point, any charges non-refundable.
Clear breakdown of costs
Clear cancellation policy
Length of programme All plans ongoing Dependent on your goals Ongoing subscription
Easy to cancel
(If cancelling within 14-day trial, otherwise you have to call customer support)
Refer-a-friend scheme
(not for customers in the UK)
Easy to include family


SW Noom Second Nature
Dietary approach Low calorie, low fat Low fat Whole foods, lower carb*
Caters to vegetarian
Caters to vegan

*For examples of recipes on the Second Nature programme, see here.


SW Noom Second Nature
Tailors the plan around diabetes
Tailors the plan around other health issues
Face-to-face meetings
(if meeting plan chosen)
Private chat with a registered dietitian or nutritionist
Developed by dietitians, nutritionists, and health psychologists
Weekend support available

Programme features

SW Noom Second Nature
Encourages daily weigh-ins
(2 apps, 1 for planning and 1 online access)
Award/prize system
Recipe videos
(Free recipe videos available on YouTube without signing up)
Exercise videos
Weighing scales provided
(on tech plan)
Tracks sleep
Tracks steps
Education of nutrition science
Counting/point system
(Free Foods®, Healthy Extras®, and Syns®)

(calories represented by traffic light system)
Food diary feature


When programmes provide price plans in different formats, it can be hard to compare prices accurately.

To make this easier, we have calculated the price of monthly digital basic price plans on each programme to show you how costs compare (as of April 2022). All admin fees are included in these prices.

For basic monthly plans, Noom is the most expensive option. On the surface, Second Nature seems slightly more expensive than Slimming World.

However, You also have the same coach throughout the Second Nature programme that you can build a relationship with, rather than an ad-hoc response from a different coach each time (Slimming World) or getting support from your group leader who is typically a past member with no nutrition training.

With Second Nature, you’ll have one-to-one private support from a registered dietitian or nutritionist. Ask questions, get advice on your meal plan, and tailor the plan to your lifestyle.

Registration to a professional body requires a nationally recognised nutrition or dietetics degree. With Noom, you’ll also have a health coach.

However, Noom coaches are not registered dietitians or nutritionists and instead have a Health Coach Certification offered by the ‘Noomiversity’, which the National Board has approved for Health and Wellness Coaches (NBHWC).

Registration to a professional body requires a nationally recognised nutrition or dietetics degree.

Weekly face-to-face sessions with a registered dietitian or nutritionist can be very expensive (£40-£100/hour). We have added a column representing this to compare costs (Weekly Nutritionist – WN).

Monthly (basic) digital subscriptions:

SW Noom Second Nature WN
Private chat with a registered dietitian or nutritionist
The same, personal coach throughout the programme
Price £20/month £47/month £28/month for an annual subscription.  £300/month

If you were to opt for the Slimming World face-to-face group meeting plan, it would be more expensive.

Example nutrition query response

Nutrition is a significant part of any weight loss journey. Therefore, it’s essential to receive accurate and reliable nutrition advice surrounding nutrition.

We asked each programme a common nutrition-related query to see how the information provided as an answer compares.

Q: Are eggs bad for your cholesterol? Should I avoid them?

Slimming World’s answer:

“I’m not trained in medical queries; I’m afraid this would be something to ask your Health Care team.”

Noom’s answer:

“No single food will stop or start weight loss. It’s all about balance! I suggest consulting with your doctor regarding specific needs (i.e. cholesterol).”

Second Nature’s answer:

“Eggs are a rich source of dietary cholesterol. It was previously thought that cholesterol-containing foods increase blood cholesterol and the risk of heart disease and strokes.

However, this is not the case, as dietary cholesterol is poorly absorbed from the digestive system. If cholesterol is absorbed, the body will produce less to balance out (and prevent blood cholesterol levels rising).

Therefore, you do not need to be restricted unless recommended to do so by your GP/Healthcare professional.

Eggs are among the most nutritious foods on the planet, providing good quality protein and containing vitamins and minerals.”

Take home message

  • When choosing a weight loss programme, it is important to consider what would fit into your lifestyle and help you achieve your goals.
  • Noom and Second Nature are both online and app-based programmes, whereas Slimming World has an optional face-to-face meeting plan.
  • Slimming World seems to focus on diet, whereas Noom and Second Nature approach weight loss by focusing on behaviour change and eating habits.
  • Noom is the most expensive programme on a monthly price plan basis.
  • Second Nature is the only programme where you get a registered dietitian or nutritionist personal health coach.
  • Noom and Slimming World have clear guides of foods to eat or avoid, which can be helpful for some but might not benefit those with an unhealthy relationship with food.
  • Second Nature provides education in nutrition science, allowing you to make informed decisions and develop a healthy relationship with food in the long term.
  • Second Nature answers nutrition queries with the most up-to-date science.
  • You can download the Second Nature, Slimming World, and Noom apps on Google Play and Apple stores.
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Write a response

Mary Cullen

15 May, 2021

I would like to try 5 day free plan


2 June, 2021

Hi Mary, thanks for your interest in the programme! Please email to request our 5-day plan 🙂 To find out more about the programme, you can take our health quiz here

Suzanne Fahey

15 May, 2021

I’m 62 healthy and moderately active working part time


2 June, 2021

Hi Suzanne, thanks for your comment! The Second Nature programme might be a great fit – to find out more about the programme, please take our health quiz here

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