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Keto Diet vs Second Nature

Tamara Willner
Written by

Tamara Willner

Medically reviewed by

Fiona Moncrieff

6 min read
Last updated June 2024

Jump to: What is the keto diet? | The pros and cons | The difference between the keto diet and Second Nature | Keto diet and weight loss | Take home message 

In recent years, the ketogenic or keto diet has been gaining popularity as an effective weight-loss strategy for treating obesity. It’s been inspired by the Atkins diet that became popular in the 1980s.

However, what exactly is the keto diet and is it a long-term sustainable option?

Our accredited dietitians have written a guide below outlining precisely what you can expect from this diet and how it compares to the Second Nature programme.

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What is the Keto diet?

The keto diet is a very low-carbohydrate diet that involves eating foods high in dietary fat and limiting your intake of carbohydrates.

While similar, it’s different to Atkins as it’s a low-carb diet with moderate protein, whereas Atkins was a high-protein, high-fat diet.

Over time, this way of eating deprives the body of its primary fuel source, glucose, and ketones (which are produced from the breakdown of fat) start to be used by the brain and other organs for energy.

This process, called ketosis, typically occurs within 2-4 days and results in rapid weight loss.

Many people on a keto diet also tend to pair it with intermittent fasting. The idea is to increase the number of fatty acids your body burns as a source of energy to increase ketone levels in the blood.

The keto diet encourages the consumption of: 

  • Extra virgin olive oil
  • Butter
  • Coconut oil
  • Cream
  • Meat
  • Fish
  • Dairy
  • Non-starchy vegetables
  • Leafy greens
  • Non-nutritive sweeteners like Stevia to replace sugar in baking

The keto diet discourages the consumption of: 

  • Whole grains
  • Beans, lentils, and other legumes
  • Starchy carbohydrates like bread, rice, and pasta
  • Starchy vegetables like carrots and parsnip
  • Ultra-processed foods
  • Any low-fat products containing added sugar

What are the pros and cons?

Recent human studies have found the Keto diet may result in several health benefits, including weight loss, blood pressure, and blood sugar levels (References 1,2,3,4).

Promising results have also been seen for various neurological disorders, including epilepsy and Alzheimer’s disease (Reference 5).

However, it’s important to note that these studies have been conducted on a small scale, and results have only been looked at in the short term, so more robust evidence is needed to draw firm conclusions about the long-term health benefits.

The keto diet can cause short-term side effects such as heart palpitations as your kidneys excrete excess minerals via your urine. Hence, you must ensure you’re consuming enough minerals such as magnesium, potassium, and sodium.

You might also experience something known as the ‘keto flu’ which also seems to be related to the excretion of minerals from the kidneys. You may also experience constipation initially, but this is common during any dietary change.

People on a keto diet sometimes also see their cholesterol levels rise. This seems to be down to a change in how the body transports the extra fat around the bloodstream.

The long-term implications of heart disease from this LDL-cholesterol rise are unclear. Many trials have shown reductions in risk factors associated with cardiovascular disease, such as higher HDL cholesterol, lower triglycerides, and lower body weight (body fat %).

Additionally, whilst this approach might sound tempting, it’s pretty challenging to follow long-term for the following reasons:

  1. It’s easy to slip out of ketosis. Eating more than 50g of carbohydrates per day (less than a bowl of muesli) is enough to take you out of ketosis, meaning you switch back to burning glucose instead of fat. From here, it can take another 2-4 days to get back into the ‘ketosis’ state.
  2. It’s very restrictive. The keto diet eliminates or restricts virtually all sources of complex carbohydrates (i.e. whole grains, root veggies, fruits, and legumes). This reduces our intake of macro and micronutrients (including carbohydrates, vitamins, minerals and antioxidants), all of which have essential health benefits and help us to function at our best.
  3. Diet isn’t the only factor that affects blood glucose levels. Research has shown that stress, inadequate sleep, sedentary behaviours, and the quantity of food we consume can also raise blood glucose levels. Therefore, you can slip out of ketosis while following the Keto diet if these other lifestyle factors are not addressed.

What’s the difference between the Keto diet and Second Nature?

The main difference is the number of carbohydrates consumed each day. The Keto diet involves reducing your intake of carbohydrates to <50g per day, whilst the Second Nature programme adopts a lower-carb approach.

Specifically, Second Nature recommends a balanced lower-carb approach with no strict guidelines on how many carbohydrates to consume.

Specifically, we recommend most meals contain 25% carbohydrate, 25% protein, 50% vegetables, and a source of fat. But this eating plan can vary, and your carb intake will depend on individual goals and preferences.

We don’t believe in only high-carb, very low-carb, or no-carb. We want to provide the proper support for everyone – and this means providing nutritional guidelines to suit you as an individual. There’s no perfect mix of the different macronutrients.

This evidence-based approach has been shown to maintain daily energy levels, improve blood glucose control and aid weight loss. Click here for an NHS-trusted diet plan.

It’s important to note that Second Nature tends not to recommend a low-fat diet as we don’t believe the strict restriction of dietary fat to be the best approach to long-term health.

Additionally, whole food sources of carbohydrates (including whole grains, potatoes, sweet potatoes, legumes, and fruit) are high in beneficial nutrients and fibre, essential for our bowel health and aiding our hunger levels (satiety). 

Another notable difference is that Second Nature is an ongoing online programme holistically addresses health and well-being.

Individuals on the programme receive daily support and guidance from a qualified dietitian and peer support from other programme members.

In contrast, the keto diet focuses purely on nutrition. Anyone can follow this diet using information available online or in books however, it’s essential to note this information is often unregulated. 

Why do people lose so much weight when they first start following the Keto diet? 

Many people report drastic weight loss during the first week on the Keto diet. However, this is mainly ‘water weight’, not fat loss. 

When we eat carbohydrates, they are either; used by the body immediately, stored as ‘glycogen’ to give us energy between meals, or a combination of both.

For every gram of carbohydrate in your body (floating or stored as glycogen), four (4) grams of water are carried with it. Since the keto diet restricts carbohydrates, the body naturally holds onto less water, resulting in weight loss. 

The Second Nature programme also reduces carbohydrates (mainly refined carbohydrates and sugar), so some water weight is lost during the programme’s first two weeks. However, the loss is not as drastic.

If you’d like to try a Second Nature meal plan trusted by the NHS, click here.

Do I need to follow the Keto diet to lose weight? 

While it may sound tempting to start the keto diet for weight loss, there’s little evidence to prove it’s superior to other weight loss methods in the long term, such as the principles followed at Second Nature. 

It’s also important to recognise that everyone is different, and there’s no one-size-fits-all approach to weight loss. It ultimately depends on what suits your needs, fits your lifestyle and can be sustained long-term.

This is why the Second Nature programme provides you with the tools and skills to learn how to make balanced choices without being too restrictive, including mindful eating and identifying distorted thoughts. 

Take home message

  • The keto diet is a high-fat diet with a very low carbohydrate intake. 
  • The Second Nature programme recommends a lower-carb diet based on whole foods eating approach but provides much more flexibility than a keto diet. 
  • There’s no one-size-fits-all approach when it comes to weight loss. The best diet for weight loss is one that you can stick to long-term.
  • Before deciding to follow the keto diet, consider whether this is a realistic and sustainable approach for you to continue long-term.


  1.  Long-term effects of a ketogenic diet in obese patients
  2. Weight loss, improved physical performance, cognitive function, eating behavior, and metabolic profile in a 12-week ketogenic diet in obese adults
  3. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum
  4. Low-Carb and Ketogenic Diets in Type 1 and Type 2 Diabetes
  5. Ketogenic Diet in Neuromuscular and Neurodegenerative Diseases
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