Dieting but not losing weight

[LoopTheLoops]

How can I be dieting but not losing any weight? I am really over weight so I was expecting quite big results quickly as is usual when very over weight but for the past week I haven’t lost anything at all? Only been on diet for 2 weeks, surely I should have lost something in a week? Very hard to stay motivated when the scales aren’t moving

Here's a pic of my weightloss chart, it's consistently heading downwards despite the day to day fluctuations, even gains and maintaining for a week or so at a time.