Environmental triggers in large part influence their behavior.

Give women a "food diary" with an image of a thin girl on the front and she will gain weight.

(Food diaries in general are a very BAD idea from square one.)

The only thing you want to record and stack is a pile of post it notes with a running calorie count throughout the day ending at a predetermined number then grab another post it note for the next day.

*Never* write down the names of food. That's foodicide.

Will the thin girl help a guy lose weight? (no study) Almost certainly not on a diary cover. That essentially triggers failure before beginning to an avg. male mind. But imagery of (some) women can increase testosterone and dopamine release which can trigger increased assertiveness and motivation. Triggers for men and women are very different.

Triggers within each of the sexes are also different and often individual. Test. But don't test too long. It's obvious pretty quickly what works and what doesn't for you as far as core-motivations.

Motivational triggers that work best are those that "keep you in line."

A picture of a cute girl on the wall will get a guy on the phone to make his sales calls but a cute girl on the fridge will ultimately make the target of the message upset. Key: Plenty of research shows that eyes watching over you work quite well.

A picture of someone's face with eyes looking down at you in the pantry will be helpful where the same photo on the fridge can become desensitized with too many viewings. eyes looking down on you are are good triggers to reign in cheating in most aspects of life.

Even atheists behave more ethically and honestly when reminded of God...and that really is a subject for another day...