My mom goes to the gym 3-5 times a week but can never lose weight. She never understands why, but I think I do. She does not eat healthy. Somtimes she says "im cheating on my diet," while she eats ice cream, pizza or other various foods. How do I tell her she needs to eat better without making it sound like:
"Hey mom, you eat like a cow!"

Any ideas?

ah , Some people treat the gym as a place to socialize.... Is she actually doing exercise at the gym? Is she doing the right exercises? Is she doing cardio?

And diet is pretty much half the battle lol.

You can exercise until you are blue in the face. However, if you are eating more calories than your body is expending, the net effect will be weight gain.

Simple as that.

Exercise isn't magic. It's merely a way to get a specific response from your body, and more relative to this thread, it's a way to help manage energy (calorie) balance.

You could try showing her how many calories she burns walking for half an hour....and how many calories a piece of pizza has. Maybe that will help her understand that diet is the main aspect, its much easier to not have the calories than to try and burn them off.

She has a personal trainer 2 times a week and when I go to the gym with her she works pretty hard, but I dont think she is honest about what she eats when writing in her journal (she has a journal that is supposed to help her keep track of calories, both input and output).

Start doing the grocery shopping or meal planning...

a) most people are truthful when they track their own food. incredibly untruthful in fact.

b) estimating caloric output is tough.

Given what you have stated so far... if your mom's goal is to lose weight, and she's maintaining or gaining, she's eating too much.

i would let her figure it out on her own.

Her goal is losing weight but, if she has been truthful with me, she hasnt been losing anything. I dont know if she has gained but if she has I dont think she would tell me.

Should I just straight up and tell her "You need to eat less or eat healthier."

I know we all cheat on our diets sometimes, but when its affecting the production of the ultimate goal isnt that too much?

Look, you started by saying:

If your mom is concerned with her weight and/or really wants to improve her appearance.... there's no question that she needs to control the way she eats. Without this control, her attempts will be fruitless. Period.

If it were my mother, I'd say something along the lines of, "Doing the same thing over and over again while expecting a different outcome is as closest to insanity as you're ever going to get."

If she's for real about her goals, she needs to be for real about her actions.

Why beat around the bush?

Your mother is a grown woman I suspect - Unless she's complaining about it -why is it your place to say anything -if she asks you for advice that's one thing.. but otherwise...

If you are trying to lose weight as well, or just going for a healthier lifestyle, you could get some books and good information off the web and just start sharing information with her....it could almost be a bonding thing. I know my mom and I are both trying to lose weight and I tell her about things I learn. My mom and I have always been very close, so we don't mind telling each other, sort of in a scolding joking way that we shouldn't be eating that....sometimes we listen to each other, sometimes we dont.

Just start doing some research, I think the best way to encourage her to be healthy is to inspire her with your own eating habits....I know that has definitely been the trend with my mom and I.

I highly recommend the book Eat to Live...it changed my life and I told my mom about a lot of the stuff I read in it.