Step 1: Food Diary

The first step in trying to change your eating habits is to start a food diary. You need data.  It can be in a notebook, or on the computer, or on your phone, it just has to include 1. what you eat, 2. your digestive response, and 3. how you feel.  It can include more, like exercise, sleep, menstruation, or medication intake, but it has to at least include those first three elements in order to give you information about how food is affecting you physically and mentally. A rough food diary template looks like this:

You can format it any way you like, this is just an example.  For myself, I just use a composition notebook that I keep in my kitchen. Write down everything you eat and how it affects you for at least a month before you try to make any behavioral change.
It is very important that you start understanding the connection between what you eat and how you feel, because every body is different: every person has different digestive evolution, different metabolic type, and different deficiencies in hormones, neurotransmitters, and enzymes.  Only you can discover what affects you negatively or positively, and you cannot rely on guilt and willpower, you must rely on the data. 
Guilt is counter-intuitive to the process of change. It does not make you want to change more, it makes you feel more weak and worthless.  If you eat a donut and all the while hate yourself because "Heather just told me this is so bad for me" you will only make yourself unhappy and uncomfortable. The dopamine surge is powerful when faced with food!  And a person feeling unhappy will be more susceptible to letting the dopamine win.  So instead, rely on the data.  Instead of white-knuckling abstinence with a giving-in to have just one bite, and then since you gave up might as well eat the whole thing, we want your experience to look like this:
"According to my food diary, when I eat white flour alone I get bloated, and when I eat sugar alone I get moody, and let's see when I eat flour and sugar together I feel happy for thirty minutes then I have a stomach ache and I get super irritated and then tired.  Let me check the ingredients on this pastry, yes, there is 26 grams of sugar and a total of 30 carbs, and refined wheat flour is the first ingredient, and oh! it's cooked in soy bean oil which on my food diary shows causes me to feel nauseous.  This will make me feel sick and cranky for sure, I choose to not have the pastry."
This will help you to have tangible proof that what you eat affects you, which will help you change with truth and self worth rather than guilt and shame. This also gives you lots of information when people ask "Why aren't you having dessert? You don't need to lose weight."   Furthermore, perhaps certain food that others deem unhealthy does NOT affect you very negatively, how will you know unless you have the data? If soy bean oil (vegetable oil) causes a flare up in pain for one person it does not mean you will have the same reaction.  As has been stated many times in this narrative, some people are far more sensitive to sugar and refined flour and "inflammatory foods" than others.  You can make the change, start with the food diary.

"In God we trust, all others must bring data." --BYU Autism Department

TOFI

Thin Outside Fat Inside. Not everyone who eats the Standard American Diet is obese, some don't even look overweight at all. Inside, there is a mess of trouble.  Being a mental health professional I have seen the ill effects on one's mood from an improper diet, and other troubles lurk as well.  I've been doing this "eat clean" for long enough that people I interact with have tried it and shared their TOFI stories, and I'd like to share them with you.  First I will tell mine.
When I made a goal at the beginning of this year to get more toned, I grossly underestimated how hard it would be. I just had to lift weights twice a week, no big deal.  What could happen, a few sore muscles for a while? I can handle that.
I had no idea that I was a TOFI. In 2013 my weight oscillated between 108 and 112, and for a while that year I was up to 115.  I know, that's pretty light, I figured I was just about where I needed to be for a healthy weight at my height (5'1").  I ran two miles three times a week so I thought I was in pretty good shape.  But when I started lifting weights, my body revolted!  I got sore muscles alright, and a nice helping of fatigue, headaches, dizzy spells, and depression. Wait! I thought exercise was supposed to make you have more energy, less depressed, and why on earth did the dizzy spells come back???  Because I was still eating refined food and sugar.
You can eat your way through any workout.  On the outside I looked thin and petite, on the inside my body was still out of balance digestively, mentally, and hormonally, and it was evident when I tried to pretend I was strong enough to weight train.  In 2011 I tried an alkaline diet of all veggies, nuts, oils, and water, and I my weight went down to 103, and my doctor was alarmed and thought I had hypothyroidism.  I felt weak and didn't have much energy, my attempts at lifting weights or doing any anarobic exercise was pitiful, so I thought it was dangerous for me to be that weight. Nope. 100-103 is actually what my weight is now, the difference is in addition to eating whole foods I'm eating sufficient protein and pancreatic enzymes are helping me digest fat, so the fat on the inside is gone and my balance is restored. I'm lifting weights regularly without ill side effects, my muscles are gaining definition, and where I could barely do my circuits with a 3 pound weight before, I've been 6 months on 5 pounds and I'm ready to move up to the 8 pound weights. And that's just one example of the benefits of being thin outside and in.  I don't get head colds! My kids will get them and all the germs just seem to pass by me.  I have less anxiety, less moodiness, increased stamina in many ways--physically and mentally.  I just hope my efforts are not "too little too late" as my pancreas does seem to be chronically damaged from 35 years being TOFI. 
Imagine my delight to know I'm not the only one who has seen positive fruits from eating clean.  I asked a client who I suspected was a TOFI to instead of having her antidepressant medication dosage increased, try to go one month avoiding sugar and refined foods to see if it helps.  She agreed, but I didn't see her again for over a month, so I figured she thought I was a crazy anti sugar extremist and would never come back. When she did make a follow up appointment she reported that she did not have to increase her medication dosage, because she noticed when she went a month off sugar the "heavy depressive" feelings went away!  She still had some anxiety, but not as much, and she was actually doing so well she didn't make another therapy appointment, but started falling apart again when she went to visit her parents and stopped being so strict on her eating.  How simple the solution! (Simple but not easy.)
I have another client who stated that she notices she sleeps better when she eats well, and her son who has emotional dysregulation disorder is less disruptive when he doesn't eat sugar. My sister Heidi started eating sugar free and got pregnant after 4 months of trying with no success, and what is more amazing, she doesn't have nearly the intense morning sickness and nausea she had with her other kids!  She attributes it to eating clean, thin on the inside!  My brother in law decided to "do a lean out" as he calls it and stop eating refined foods and sugar, and he not only lost a lot of weight but reported that his allergies this season somehow aren't as bad as they usually are!  Amazing and wonderful!  I love hearing stories about the benefits people experience from eating clean. It's not just about the weight, although that is important to control, it's about overall health.  Lets be TOHI (thin outside and healthy inside) not TOFI!
"You already know that your food choices impact the blood sugar-regulating hormones insulin and glucagon, but they affect a myriad of other hormones as well.  From health challenges like acne, hypothyroidism, poly-cystic ovarian syndrome, low testosterone, or even fertility complications to mood swings, painful periods, or menopause, I always recommend getting blood sugar regulation under control as the first step.
"Here's the thing about blood sugar regulation: If its not working properly, then the rest of your hormonal balance can and likely will suffer."--Diane Sanfilippo

Balance

I have a beloved cousin who lives in Oklahoma who I grew up with, and his birthday is 5 days before mine so I always remember him on his birthday and call him, and if I don't reach him he usually calls me on my birthday 5 days later. This year we were talking and he asked if I was still strict off sugar. I told him I was even more strict off sugar than I used to be, and he applauded my effort, but warned me about getting to extreme.  "I have to have my dessert each night, that's my splurge." I told him that having half a tortilla or sauce on my chicken was splurging for me, what he has for dessert is simply going overboard. "No, Heather what you do is too much." We kind of left it there, but I later pondered on how differently he and I defined balance in our intake.
Fast forward to this scenario a week later: I registered for an Autism conference at BYU and always look forward to those events for two reasons, 1. I get to spend the day with my good friend Shannon, and 2. there is a luncheon catered for participants. I got ready bright and early and had my sensible egg and green shake breakfast, made sure I had nuts in my purse and water with me, and eagerly drove to BYU. I was confronted with a continental breakfast at the registration area: bagels, cream cheese, and juice.  Strike strike strike. Good thing I ate before I came. But since I told the dining staff when I registered for the lunch that I don't eat sugar, surely I will be able to have something at lunch. I met Shannon and enjoyed the information and catching up with her. When we went out on the beautiful patio under a covered pavillion with Y mountain in view for lunch, I started to panic. All the lunch settings had been preset with plates of lettuce, with a cake above the plate, rolls on the table, and salad dressing. Three strikes again.  I started to choke down my plain lettuce trying to concentrate on my visit with Shannon instead of the greens, and again informed a kitchen staff I don't eat sugar.  Obviously they don't consider dressing, cake, and rolls sugar. They brought out the main course, chicken with white sauce and pasta (strike), covered with sun dried tomatoes and mushrooms.  Looks delicious.  As I pushed my pasta aside and wondered what the sauce was made with but knowing I had to eat something, I devoured my chicken.  Meanwhile a staff had filled my cup with sparkling apple cider. Strike 5.  I looked around the table and people eating the rolls, cake, juice, and pasta.  I felt the familiar tug of despair that I could not join them, combined with the knowledge of the unknown consequences they were falling prey to, and top that off with my own guilt for eating food of which I didn't know what the ingredients were. Shannon engaged me in conversation as to why I don't eat the refined carbs, and I felt even more mortified talking to her about the dangers of sugar consumption while she was eating cake.  She didn't seem to mind the side order of guilt, she was very understanding, and thankfully the chicken was sufficient to fill me up.  When 3:00 came they announced a cookie break in the next room. 9 strikes in one day.  I was emotionally spent.
But the day wasn't over. That evening I had the privilege of taking my Grandma to a play at BYU. We didn't have time to go to a sit down restaurant but I had to provide dinner for us, so I reluctantly took her to a fast food place, she ordered a chicken sandwich and I got a baked potato and chili.  Her dinner looked so good, with the bun and honey mustard sauce, and I had to choke down chili that probably had some sort of covert sugar in it that I didn't know about, so I was splurging but at least I was trying to avoid refined carbs, and it didn't even taste that good. Strike 10. And I burned my tongue. I had had it.
In the movie "Fed Up" it talks about this very thing, our bodies can handle a little refined sugars and flours but we are eating far far more than a little every day, and that Friday at BYU I witnessed the overflow. The World Health Organization suggests 6 teaspoons or refined sugars a day as a maximum, yet a typical conference attendee who would have eaten the bagles, cream, juice, rolls, dressing, cake, pasta, sparkling cider, and cookies, and then went home and ate out at Wendy's with their family and had a chicken sandwich, would have consumed over 40 teaspoons of refined sugars in one day. Who is the extreme one now?
The labels on food have a percentage next to the ingredients contained therein, this percentage represents the WHO daily recommended intake for that ingredient.  Sugar has no percentage next to it, because if it did, the percentage would be so high it might discourage patrons from purchasing that item.  For example, if we are only supposed to have 6 teaspoons of sugar a day, then putting three tablespoons of cream cheese on your refined flour bagel (sugar 90%), having 2 cookies (sugar 120%) and soda with your lunch (sugar 200%), you've crossed your threshold or the recommended intake by about 200%.  Its no wonder that what used to be called "adult onset diabetes" is now diagnosed in over 50,000 children and adolescents.
So when my cousin tells me he has to have his dessert every night, I'm not faulting him for having a little ice cream and chocolate sauce (sugar 180% of daily recommended allowance). I'm thinking about the toast and jam he had for breakfast (sugar 60%), the gatorade, ketchup and hotdog bun he ate for lunch (sugar 150%), the teryaki sauce he had on his meat and veggies and white rice he had for dinner (sugar 100%), and finding it odd that he thinks I'm the one out of balance. But again, why bring that to his attention?  All it will do is give him a side order of guilt, because when confronted with refined sugars, the brain will always choose in favor of intake over abstinence. Unless you like me got fed up.