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Talk to some women who you trust and talk about what changed in your life and look at why you gained the weight, beyond the obvious. Look at the biological, hormonal drive to eat more and the link to feeling tired and losing motivation. You are not alone in experiencing this when your body is not operating as it was designed, biologically.
Fill up daily first on your vegetables with every meal, even breakfast! Even include a vegetable in every snack you eat (non-starch). Women generally do not eat enough fiber so go for high fiber carb options, and fuel up on lean proteins! You can do this, and it may be a healthier diet than what you were eating in your pre-Depo days!