Higher stress levels can lead to a diet failure.
Diets don’t reduce stress. They not only increase stress, but they also reduce your ability to adapt correctly and may even increase your stress. Trying to lose weight takes a high-level fo motivation and is demanding. It is a lot of work to focus in on healthy food shopping, cooking, and exercise and these activities may actually add to the daily burden of life. Some welcome new stressors, but others may be overwhelmed by the added requirements that this adds. I am not one of those people, and I often fail to have long lasting changes when I start a lifestyle change during a period of stress.
We often try to start a diet after New Years, but this might be the worst time to try a change because it is also one of the most stressful periods of your life since we often have piles of debt after the holidays. I would recommend that you plan to start a diet in August or September when the stress is lower. Then again, if you operate on a fiscal year and have to write and end of year report, that may not be a good time for you.
The bottom line: Plan you diet around periods of high stress and maximize your success.