Design Guidelines and Principles in App Lifesum

Lifesum is a weight control App, which serves to record daily food intake and quantity of exercise. Users can know their eaten and burned calories, intake of carbohydrates, fat and protein with it. They can also set a goal of weight and Lifesum will help them control intake and trace the change of weight. Weight control is always boring and even painful, but this well-design App eases users’ pain and resistance to weight control by its design.

Some principles in Lifesum:

There are 5 buttons(icons) in the bottom of the App and each of them represents a different page. When you in the page Diary, the button Diary is green and others in gray (except the “Plus” button which is always green). This is an indication of location. This design illustrates principle Conceptual Model. The long-term application and website using gives users a conceptual model that if a tag on a website or a button in an App has a different color from others, it indicates the place the user is. Every time the user switches pages, the button of the page where the user is will turn green and others become gray. This gives a feedback to user: you have switched the page successfully. All functions in this App is visible and every function maps to a button or a link. Nothing will be out of expectation in Lifesum.

Some guidelines in Lifesum:

Record function is located in two different pages, however, there is only one record subpage for users recording their weight, daily intake and exercise. This design not only makes sure that users can find the functions they need easily, but also makes sure the consistency in data entry. If users find that they record in different pages, it will cause confusion. In addition, the designers of this App design it with consistent color, layout, terminology and font.

All terms in this App are easy to understand: they are as same as our everyday words. Button “Diary” is for your record; “Plans” is for weight control plan; “Me” represents personal information. Anyone can use it with intuition. This intuitive design style guarantees usability. In the Recipes page, thumbnail pictures serve as a button and preview for users. This is a very effective way for navigation and interaction. Just liking shopping in a supermarket: finding what is needed or what looks great for you and picking it up directly. Every action is reversible in this App, which means that every time you record a mistake number or choose a recipe, but you don’t like it soon, you have unlimited numbers of chances to correct and change them. Lifesum is a memory offloading application for people who use it to record. Moreover, its design also helps us offload short-term memory. It’s safe to say, you don’t need to memory anything in this app. All the design in the App ensures users use it fluently without memorizing. There are no complicated functions that need explanation and no terms unfamiliar for users.

Designing principles and guidelines are useful for UX designers and product designers to elaborate their design. However, a satisfactory design also needs users’ personas, iterative usability test and so on. In a word, designing principles and guidelines are important, but they could not guarantee a satisfactory design.



Ben Shneiderman, Catherine Plaisant, et al. Designing the User Interface: Strategies for Effective Human-Computer Interaction. 6th ed. Boston: Pearson, 2016. Excerpts.

Ben Shneiderman’s Eight Golden Rules for Interface Design (on one page)

Apple Developer: Human Interface Design Guidelines