The Hacker's Diet looks at dieting and weight control from an engineering and management point of view. In a very simplified nutshell (as the actual free document itself is 336 pages), it is about calories in versus calories out. While it goes beyond that, I couldn't explain in a short time here. Exercise is not a part of this diet, though it addresses it and encourages it.
It treats all calories equally, though I feel the differences between calories from fat differs from the calories from carbohydrates differs from the calories from protein. It also tends to underestimate the calorie burn from exercise, though it is dependent on your weight.
The part I like best about this is the looking at changes in weight on a graph along with the "line smoothing" graph. Weight can go up and down depending on how much water is in your body. This can be maddening when you are dieting, feeling that you should have made positive progress. The line smoothing shows the weight changes as a trend, so even if your weight goes up from the previous day, the trend can still show weight going down, which can help people psychologically.
Also included on the Hacker's Diet site are Excel spreadsheets where you can track your weight and see the trend graph as well. A version that works with OpenOffice.org (and I imagine LibreOffice, though I have not tried it yet, can be found at http://jon.thysell.us/software/hackersdiet/.
I've been using the spreadsheet for probably a bit over a half year and seriously been dieting for almost a year. I've already lost 40 pounds from a combination of using Fitbit to track how much walking I get done, determining how many calories I need to eat for weight loss with the Freedieting calorie calculator, and tracking my weight in the Hacker's Diet spreadsheet.