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The Thonon diet

The Thonon diet is all the rage – not least because it promises to help you lose 10 kilos in just two weeks! But like all strict diet plans, it can lead to fatigue, muscular weakness and binge eating. Read on for the pros and cons of the latest crash diet.

Key principles

The Thonon diet
© Thinkstock

The Thonon 14-day eating plan is a crash diet. It’s a low-calorie plan that reduces fat and sugar and increases protein like lean meat and fish.

You get a 7-day menu plan that must be followed to the letter for two weeks, with a period of stabilisation afterwards. If dieters haven’t reached their goal weight at the end of the two weeks, you can repeat the plan. However, it shouldn’t be continued after the second two-week period.

The plan

The 14-day eating plan is based on the following daily menus: 







Day 1

-Coffee/tea (no sugar)

-2 hardboiled eggs

-Spinach (as much as you like) with no fat

-1 large steak or 3 small burgers

-Leafy salad with celery dressed with lemon juice or olive oil

Day 2

-Coffee/tea (no sugar)

-Some milk

-Grilled steak

-Green salad with tomatoes (no dressing)

-Fruit (as much as you like)

-Boiled ham (as much as you like)

Day 3

-Coffee/tea (no sugar)

-1 small wholegrain roll

-2 hardboiled eggs

-Green salad with tomatoes (no dressing)

-Boiled ham

-Green salad (no dressing)

Day 4

-Coffee/tea (no sugar)

-1 small wholegrain roll

-1 hardboiled egg

-Raw carrots dressed with lemon juice (no oil)

-1 slice of gruyère cheese

-1 natural yoghurt

-Fruit (as much as you like)

Day 5

-Coffee/tea (no sugar)

-Grated carrot with lemon juice

-Fish cooked in stock

-2 tomatoes (no dressing)

-Grilled steak

-Green salad dressed with lemon juice or olive oil

Day 6

-Coffee/tea (no sugar)

1 small wholegrain roll

-Grilled chicken (as much as you like)

-2 hardboiled eggs

-Carrots (raw or cooked) with no fat

Day 7

-Coffee/tea (no sugar)

-1 large steak (grilled)

-Fruit (as much as you like)


Eat what you like in moderation, but don’t drink alcohol.

Snacking in between meals should be avoided during the diet. Any food not in the plan is off limits. Make sure you don’t add salt to any of the dishes.


It’s important to make sure you don’t just put the weight back on after the two-week period, whether you’ve reached your target weight or not. To achieve this, you need to stick to a specific calorie intake during stabilisation: 

  • 1200 kcal for women, but you can eat up to 1500 kcal if you’re hungry.

  • 1500 kcal for men, but you can cut down to 1200 kcal if the menus seem too heavy.


1200 kcal plan:



  • Coffee/tea (no sugar)

  • 1 low-fat dairy product

  • 1 slice of wholemeal bread with 10g of margarine

  • 1 fruit

Mid-morning/afternoon snack (optional)

  • Coffee/tea (no sugar)

  • 1 low-fat dairy product


  • Crudité vegetables with 1 teaspoon of olive oil

  • Fish or lean meat (100g-150g)

  • Cooked vegetables (with no fat)

  • 1 light dairy product

  • 1 fruit 


  • Vegetable soup (with no fat)

  • 1 small potato

  • Fish or lean meat (100g-150g)

  • Cooked vegetables with 10g of margarine

  • 1 slice of wholegrain bread

  • 1 small piece of fruit


1500 kcal plan:


Follow the same menus as the 1200 kcal plan, but include a portion of carbohydrates and 10g of margarine in your breakfast.

During the 14-day plan and the stabilisation period, you’re advised to take multivitamins and omega 3 to minimise the risk of deficiency. 

Does the Thonon diet work?

According to the diet’s creators, you can expect to lose up to 10kg in 14 days. In practice, people lose around 5kg or 6kg on average. During the stabilisation period, you should continue to lose weight at a rate of 1kg a week.

Reading dieters’ experiences online in different forums, it’s clear that the amount lost varies significantly from person to person. While some achieved the weight loss promised, others barely managed to lose 1kg a week. Others said they gained weight again during the stabilisation period.

As with any type of diet, men generally lose more weight than women. On top of this, the Thonon diet is less effective for those who have followed a strict low-calorie diet before.

You should remember that with crash diets you don’t just lose body fat but also muscle mass. The lack of salt in the Thonon diet also means that you will lose water much more quickly.

Pros and cons

So what are the advantages of the Thonon diet?

  • The Thonon diet has few advantages aside from helping you lose weight quickly. It appeals to people who want to slim down for a special occasion (wedding, holiday etc.). The fact that it’s so strict and leads to fatigue means it’s worth limiting the diet to just one week. 

  • It can be used to kickstart a more long-term weight loss regime for those who have difficulty losing weight. Again, a week is enough.

  • The creators of the Thonon diet advise consulting a doctor and getting a full medical check-up before starting the plan. 


And the disadvantages?

  • The diet’s creators admit that the Thonon diet isn’t very varied and dieters may get bored quickly. They also warn of the consequences of crash dieting for your body’s health, citing digestive problems and cognitive difficulties. The diet isn’t recommended for children, pregnant women, the elderly or people with sensitive stomachs.

  • The menus for the first 14 days make up between just 600 and 800 calories a day, which is three or four times lower than the daily recommended intake for adults. Sugar is off limits and the diet doesn’t include very much bread or fruit, either. This means dieters only get 100g of their recommended daily intake of carbohydrates which are essential for brain activity. The Thonon diet can lead to extreme fatigue, migraines and even illness as a result. Your body will use up all its glycogen reserves (carbs stored in the body for use by the liver and the muscles), and so the diet is not suitable for even normal levels of activity, let alone sport, as you can see from dieters’ testimonies in forums.

  • The dramatically reduced calorie intake means proteins, which are normally used as protective nutrients, are used instead to fuel the body. The Thonon diet can therefore lead to muscular weakness and a decrease in basal metabolic rate, reducing energy needs.

  • The diet isn’t varied and excludes a number of different foods. This means you’re likely to suffer from deficiencies in calcium, magnesium, vitamins B1, D and E, essential fatty acids, omega 3 and omega 6. The recommended supplements will only partially cover your body’s needs.

  • As with all crash diets, the Thonon diet can trigger or aggravate eating disorders like compulsive eating and bulimia. According to the discussion forums, the ‘own choice’ option can lead to bingeing.


The stabilisation period where dieters consume 1200 kcal or 1500 kcal a day is still a low-calorie diet and has the same drawbacks as the 14-day plan.

Overall, the Thonon diet is a punishing regime that can lead to yoyo dieting. It alters your metabolism and can even mean you put on more weight over the long term.


Florence Daine

Posted 24.04.2013


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