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The 3 Day Diet

WebMD Medical Reference
Medically Reviewed by Dr Rob Hicks

The 3 Day Diet touts quick weight loss, cleansing, lower cholesterol, and more energy.

It's a strict plan that must be followed exactly for three days. If you still want to lose more weight, you're supposed to eat normally for at least four or five days before starting again.

half of grapefruit

The 3 Day Diet promises up to 10 pounds of weight loss in three days. But most of that weight is water, not fat, so the results aren't likely to last.

What you can eat

The 3 Day Diet is very specific about portion size and the foods it includes.

The combination of the suggested foods supposedly creates a unique metabolic reaction that boosts fat burning. But there is no explanation of how that happens or proof that backs up those claims.

The plan also calls for dieters to drink 4 cups of water or calorie-free drinks daily.

Expert assessment

We asked British Dietetic Association spokesperson, Alison Clark to assess the 3 Day Diet.

"Unfortunately, this 3 Day Diet seems to be another faddy diet perhaps gaining recent popularity due to the 2:5 diet," she tells us.

"To claim such a dramatic weight loss is misleading to the consumer. The reason it causes weight loss is because the diet is so low in calories, not because, as it claims “unique metabolic reaction and boost fat burning”! There is no science to substantiate this and if it sounds too good to be true - it usually is! The likely reason for people following this diet to lose weight is because it is low in carbohydrates and hence a large percentage of the weight loss is water, and not the desired fat loss.

"It is worrying to see the 3 Day Diet advocate foods high in saturated fat (e.g. cheese) when the diet claims to lower cholesterol. We would certainly encourage anyone who wants to lower their cholesterol and aim for optimal health and wellbeing to limit their saturated fat intake. Also, Day 2 is very low on fruit and vegetable intake which is again worrying as these foods provide the bulk without the calories, great for weight loss, so I would probably expect dieters following this plan to feel hungry!

"The diet is very prescriptive and also very strict, which provides no encouragement for the dieter to change eating behaviours to manage their weight effectively long-term."


In summary, the 3 day diet restricts calorie intake and doesn’t follow healthy eating guidelines necessary for a healthy weight and a healthy body. The rapid weight loss is due to water released from the liver and muscles, which quickly returns once normal diet is resumed.

 Dietitian reviewed by Catherine Collins RD

Reviewed on May 09, 2017

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