The 80/20 Diet Rule

The 80/20 diet is a modern form of dieting that is far more flexible than many of its peers.
Image Credit: Olha_Afanasieva/iStock/GettyImages

The 80/20 diet, also known as the Pareto principle diet, is a modern form of dieting that is far more flexible than many of its peers. It is based on the theory that 80 percent of results are from 20 percent of causes, and is potentially much easier to adapt to than more stringent eating plans.


Read more: Does The 80/20 Rule Work for Everyone?

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What Is the 80/20 Diet?

The 80/20 diet is fairly simple in its mechanics. All it comes down to is: For 80 percent of the time you eat nutritionally valuable food (such as fruits, vegetables and lean proteins), and for 20 percent of the time you can consume whatever you please (like that slice of chocolate cake you've been thinking about, for example).

The 80/20 diet is popular because it isn't as restrictive as other diets of its kind. You can still eat whatever you find yourself tempted by, as long as it is eaten in moderation and portions are kept reasonably small.

For instance, say you come home from work having eaten nutritionally well all day. You want a slice of chocolate cake and a glass of red wine to treat yourself and unwind. Seems understandable, except that having both of these items would likely undermine how well you had eaten throughout the day.


Eating 80/20 wouldn't mean you could not enjoy these treats, it would just mean you couldn't have them both on the same day. Have the chocolate cake today, and save the wine for tomorrow — you get to enjoy both without ruining your positive diet habits.

Read more: How Does Healthy Eating Affect Physical, Mental and Social Health?

Advantages of the 80/20 Diet

The strongest benefit associated with the 80/20 diet could be its unique flexibility. Its parameters simply state that for 80 percent of the time you must eat healthy, and 20 percent of the time you can eat freely. "Healthy" is a fairly subjective term, meaning there are many ways it can be interpreted and squeezed into even the busiest of schedules.


Unlike other restrictive diets, it's less of "I can't eat that" and more of "I can't eat that today because I have already treated myself, but I can have it tomorrow."


A study published in the November 2017 issue of the_ Journal of Obesity & Weight Loss Therapy _conducted a study of 29 college students in which 17 participated in the MyPlate diet and 12 participated in the 80/20 diet. The aim of the study was to assess the effectiveness of these diets on physiological and psychosocial factors — but so many students dropped out of the study that the results were not clinically significant.


This led to an unanticipated conclusion: Of the participants who dropped out, 10 were from the MyPlate group and only two were from the 80/20 group. At the end of the study when the participants completed their questionnaires, many highlighted that the MyPlate diet featured unreasonable demands that made it difficult to stick to.

This feedback, paired with the dropout rate, led the researchers to conclude that the 80/20 is a far more applicable diet for the general public to follow when compared to similar diet-restriction plans.


The 80/20 diet helps with weight loss because it aims to reduce the amount of saturated fatty foods in your diet. According to MedlinePlus, high-fat foods, such as pizza, baked goods and fried foods, are some of the worst offenders for weight gain. On the 80/20 diet, you should only be consuming these foods 20 percent of the time, which should greatly reduce your overall fat intake.

Downsides of the 80/20 Diet

Ironically, what makes the 80/20 diet so desirable also has the potential to be its downfall. The flexibility associated with eating 80/20 can mean that unless you are highly disciplined in your commitment to the diet, you may end up consuming more unhealthy foods than you would on a more restrictive diet.


This is why you should aim to practice the diet every day. Not only does this make it more achievable, but it also increases the chances of it becoming habitual. A study published in the British Journal of General Practice in December 2012 explored the ways in which repeated behaviors become habits over time. It found that daily habits repeated over a period of 10 weeks should eventually become habitual, requiring much less deliberate thought.


In addition to this, abiding by the 80/20 diet daily instead of weekly can minimize the likelihood of overeating unhealthy foods. When practiced weekly, the 80/20 diet works when you eat healthily through the weekdays and treat yourself on the weekends.


It seems ideal in theory, but what it can often result in is an overindulgence as you have restricted yourself all week. This also doesn't lend itself well to longevity, as you may get frustrated at the strict rule of weekend-only treats and give up on the diet entirely.

Making your positive diet habitual is best if you want to keep the excess weight off. A study featured in the January 2019 issue of the Journal of Medical Clinics of North America explored the challenges of long-term obesity treatment, and how many people regain the weight after rapid weight loss. Long-term weight loss requires long-term maintenance, and this is best achieved by lifestyle changes as opposed to quick fixes.

An additional study published in the July 2017 issue of the International Journal of Endocrinology Metabolism found that while rapid weight loss and slow weight loss both demonstrated relatively equal results, the slower weight loss improved body composition overall.

Foods for the 80 Percent

A term like "healthy" can be hard to pin down, which is partly the problem with the 80/20 diet. It lacks specific discipline. Luckily, there are resources at hand that can help give you a clear sense of which foods should make up the 80 percent of your diet.

According to the Dietary Guidelines for Americans, 2015-2020, these food groups are some of the most nutritionally valuable that you can include in your 80/20 recipes:

  • Vegetables: High in numerous vitamins and minerals such as fiber, potassium, vitamin A, vitamin C, vitamin K, copper, magnesium, vitamin E, vitamin B6, folate, iron, manganese, thiamin, niacin and choline. Vegetables are a staple of any healthy diet. Dark greens provide the most vitamin K; red and orange vegetables provide the most vitamin A; legumes provide the most dietary fiber.
  • Fruit: All varieties of fruit —

    frozen, canned and fresh —

    are beneficial to the diet, and 100 percent fruit juice can also be highly beneficial as it has no added sugars or preservatives. The key nutrients in fruit include dietary fiber, potassium (from bananas) and vitamin C (citric fruits such as oranges and grapefruit).

  • Protein foods: A wide range of foods can provide necessary protein, both plant-based and animal-based. Meat products provide the most zinc; poultry provides the most niacin (a B vitamin related to energy levels); seafood provides the most vitamin B12 and vitamin D.

The key to any diet is achieving balance, not only so that your body receives a variety of the nutrients it requires, but also so that you can enjoy what you eat without feeling bored. The key to eating 80/20 may be the effort to enjoy the entire diet, not just the 20 percent made up of treats.




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