You’ve heard of the 80/20 food rule, right? Eat healthy, clean, sensibly between Monday to Friday and then treat yourself over the weekend. What everyone has for their treat may vary. It could be takeaway, alcohol, something sweet or perhaps a combination of these. I often get asked “That’s OK – isn’t it?” “It’s the 80/20 rule, right?”
When the 80/20 rule is extrapolated to food and eating, the idea is that you choose to eat healthy foods 80 per cent of the time (Monday to Friday is usually mentioned) and indulge in your favourite treats 20 per cent of the time (usually taken as Saturday and Sunday), making it easier to stick to a long-term, healthy eating plan. Well, in theory at least.
This makes me wonder:
- is eating healthily Monday to Friday an 80% ‘chunk’ of our week?
- is the 80/20 rule even applicable to our eating to begin with? Is it about the proportion of time we eat ‘on-track’ to the time we eat ‘off-track’?
- is eating healthily Monday to Friday and adding in treats on the weekend an effective way of eating for good, long-term eating habits and to maintain a healthy relationship with food?
- can the 80/20 rule be applied to exercise?
80% of our week
With seven days in a week, one day makes up about 15% of the week, so Monday to Friday would actually be about 70% of the week and Saturday and Sunday would actually be closer to 30% of the week. That’s not exactly 80/20. So you would actually be eating ‘on-track’ 70% of the week and ‘off-track’ 30% of the week. In which case, eating well Monday to Friday should be described as a ‘70/30 rule’. However, given that many count Friday night as the start of the weekend, then the number of ‘off-track’ days could be as many as 3 out of 7 or about 40% of the week. Hmmm. Now that’s starting to look more like a 60/40 rule!
The principle of the matter
The 80/20 rule is another name for the Pareto principle which came about from an observation that for many events, roughly 80% of the effects come from 20% of the causes. Pareto, after who it is named, showed that approximately 80% of the land in Italy was owned by 20% of the population. This phenomenon is also noticed in agriculture, in management and in business.
The 80/20 rule is therefore not about the proportion of the week or time spent on one of two options and dividing your time in an 8:2 ratio. It is more about, cause and effect. To apply this principle to food would be something like ‘80% of your indulgence foods are eaten over 20% of the week.’ So, if you ate healthily the whole week and had treats over the weekend, then it could be true that 80% of our excess calories come from our weekend eating habits.
Does it work?
If you ate well for 5 days and allowed treats on the other 2 days, would you be ‘better off?’ Is following the 80/20 style of eating better from a weight perspective? Are there other health benefits to an 80/20 diet? Interestingly, a recent study done with 3 groups of mice over 16 weeks included:
- mice who were fed unhealthy food (cake, biscuits, meat pies, chips)
- mice who were fed a low fat diet for 4 days and high fat foods for 3 days a week and
- mice receiving a continuously healthy diet.
The mice in the second group gained less weight than the mice eating unhealthy food, however, the mice in the second group ate 30% more calories than the mice in the third group. Other measures such as leptin, insulin and weight were in between those of the first group and the third group. If the second group’s diet is likened to eating an 80/20 diet, then maybe the consequences are not as trivial as previously presumed.
You would think that if you ate well for 5 days and allowed treats on the other 2 days, that fewer indulgence foods are eaten. However, deferring our treat when we really feel like it can be counter-productive.
Say it’s Monday and you feel like a biscuit, but go without on Monday, then go without the following day, go without for the whole week (because “I can’t have it until the weekend”). But then on Saturday, on your “allowed” day, when you finally do have the biscuit it may not provide the same enjoyment. You may need a greater amount to give the same satisfaction or you may simply have a greater amount because you feel you deserve more for your enormous willpower! This sort of eating can start, or aggravate, disordered eating.
A more appropriate eating plan would be one which considers the proportion of core foods (vegetables, fruit, grains, dairy and meat/legumes) to discretionary foods (baked goods, alcohol, sweets) on a daily basis.
For an average, middle-aged woman, the Australian Dietary Guidelines recommend one discretionary food may be included daily, if and when desired. For example, this could be a small muffin, a Fun-size chocolate bar or a standard drink of wine.
What about exercise?
The 80/20 rule has also been applied to exercising. As with food, you would exercise Monday to Friday and have a break from exercise on Saturday and Sunday. The same dilemma could occur. If days are labelled ‘exercise days’, then you will see exercise as a chore. It may also create feelings of guilt if it is not done. On the other hand, the weekend may be labelled as ‘exercise free’ but you may be more motivated or have more energy because you’re not as tired or stressed and therefore enjoy it more.
Words to the wise
Instead of focusing on eating well for 5 days a week (and relaxing our eating habits for the rest of the week) it may be more effective to focus on the proportion of core foods to treat foods we eat each day.
Furthermore, because the ‘80/20 rule’ lacks enjoyment and the “because I choose to have/do it now” factor with both food and exercise, it may create unnecessary feelings of deprivation and create distorted eating and exercise habits. Incorporating a small, special indulgence into our daily eating, if and when we feel like it, can lead to a happier and healthier relationship with food. Similarly, incorporating exercise when we choose to, will enhance our enjoyment and ultimately improve commitment.