The usual explanation for why you keep going back to processed food is that you lack discipline. It is a convenient story for the people who make the food, and a useless one for you. It is not even accurate. When 281 sets of findings from 36 countries were pooled, about 14% of adults and 12% of children met the criteria for addiction to ultra-processed food on the standard questionnaire, about the same share as for alcohol among adults, and not far below tobacco. That is not a weakness of character. It is a design working as intended.
The difficulty has causes, and the causes have a timetable.
Here is the best evidence that the hard part ends. A group of young adults cut down on salt and kept it down for five months, while a second group ate as usual. By the end, the same crackers tasted saltier to the first group, and the amount of salt they found most pleasant in soup and crackers had fallen. The second group's taste had not moved.
Nothing about their willpower changed. Their tongues did.
That is the pattern for most of what makes processed food hard to leave. The pull is real, it comes in a predictable order, and each part of it fades on its own clock. Knowing which part you are in turns "I am failing" into "this is week two".
Why it feels like failure
The body did not adapt to processed food in one piece. Blood sugar control, the brain's reward system, hunger hormones and the gut each adjusted to their own kind of input, and each will adjust back on its own schedule.
Take everything out at once and you ask all of them to recalibrate together. The blood sugar dip, the caffeine headache, the cravings and the tiredness arrive as one heavy signal, and it reads as the body rejecting the change. It is not a rejection. It is a renovation, with every room done at once: several separate processes, each of which would be manageable alone.
They also recover at different speeds. Blood sugar settles first. The gut bacteria move fast too: Your Genes Aren't Your Destiny: How Much of Your Health Is Up to You has the volunteers who ate only animal foods or only plant foods, and whose gut bacteria shifted quickly, by enough to swamp the differences between one person and the next. Cravings take longer. Body fat takes years. So six weeks in, you can feel better in one way and no different in another, and conclude that nothing is working while most of it is.
And a failed attempt is not wasted. Whatever the body adjusted before you slipped does not reset to zero. The next attempt starts from wherever the last one stopped.
Why some foods pull harder
Some foods are much harder to give up than others, and they tend to be the ones that hit several pulls at once.
Pizza stacks refined starch, which lifts blood sugar fast, with fat and salt at the level the food industry calls the bliss point. Sweetened milky coffee stacks caffeine with sugar. The foods that feel impossible to stop are almost always doing two or three things at once. A pizza is less a food than a committee.
The term "bliss point" belongs to Howard Moskowitz, an American who tested and tuned food products from spaghetti sauce to soft drinks and used it for "that sensory profile where you like food the most". Chris van Tulleken's is a whole book on why these foods are so hard to stop eating.
The pull can be measured. Why People Fail at Weight Loss (And How to Succeed) has the adults who lived in a clinic for a month and ate about 500 calories a day more from an ultra-processed menu than from a real-food one matched for calories, sugar, fat, fibre and salt. They gained 0.9 kg on it, and lost 0.9 kg on the real food.
Dairy is sometimes blamed for a pull of its own: as milk protein is digested, it releases fragments that can act on the body's opioid receptors. How to Outsmart Cravings and Make Healthier Choices Without Relying on Willpower, linked below, has the honest state of that idea: the fragments are real, and a proven effect in people is not.
So the order you take things out matters as much as the taking out. Steady blood sugar makes every later change easier, so it comes first.
The first days: blood sugar and caffeine
The first rough patch has two sources running together.
Take out the sugary drinks and sweet snacks, and blood sugar loses the spikes it has been running on. The dips in between feel like hunger and fatigue.
If those drinks carried caffeine, you get its withdrawal on top. How to Quit Coffee: Getting Through Caffeine Withdrawal has the timetable: symptoms usually begin 12 to 24 hours after the last caffeine, peak over the next day or two, and fade within about two to nine days, with headache in about half of regular drinkers who stop suddenly.
Both produce headaches. Both produce fatigue. Together they feel like the body failing. Two separate hangovers, arriving on the same morning. Separately, each passes within days. If you can, take the caffeine down on its own, before or after the sugar, so you know which headache is which.
The first weeks: the switch away from carbohydrate
The next patch comes when the bread, pasta, rice and sugar go, and the body has to get used to running on fat.
Part of the early tiredness is water. The body stores carbohydrate as glycogen in the liver and muscles, and each part of glycogen is held with three to four parts water, along with potassium. As the glycogen is used up, the water goes, and minerals go with it. That is why the scales drop fast at first, and why you can feel flat, headachy and light-headed.
The Quiet Signals of Mineral Deficiency has the rest: as the water goes, salt, potassium and magnesium leave with it, and in people's own accounts the "keto flu" peaks in the first week and fades within four.
The fix is plain. Salt your food, drink a mug of salted bone broth, and eat meat, fish and eggs, which bring their own potassium. make the broth in a minute when there is no pot on the stove. The tiredness is the switch happening. It is not proof that the body needs bread. It is proof that the body was used to it.
The switch has an upside for hunger. Thirty-nine adults lost 13% of their weight on an eight-week ketogenic diet of very few calories. Weight loss normally drives up ghrelin, the hormone that says "eat". While they were in ketosis, that rise was suppressed, and they rated their appetite lower than they did once ordinary food came back.
The middle weeks: the cravings
Once blood sugar has settled, the cravings take over as the main event. They feel like hunger, but they are specific: the particular biscuit, the particular takeaway, at the time and in the place you used to have it. Your stomach is not asking. Your habits are.
So find the habit. The Real Reason Your Habits Never Stick has the week of writing down what happened in the five minutes before each urge, and the 122 programmes with 44,747 people where keeping a record explained more of what worked than any other technique.
They do fade. How to Outsmart Cravings, linked below, has the people who ate less for twelve weeks or more, across eight groups, and whose cravings went down, for sweet, fatty, starchy and fast food alike. The Hidden Science of Sugar Cravings, also linked below, has the low-carb group whose cravings for carbohydrates and starchy food dropped further than the low-fat group's over two years.
Alcohol keeps the cravings company. Why People Fail at Weight Loss, above, has the 12 tests where people who had an alcoholic drink ate about 80 calories more food on top of it. Cutting processed food while still drinking most evenings makes every stage harder.
Sleep makes every wave bigger
A short night makes each of these harder at once. Why People Fail at Weight Loss, above, has the adults on the same reduced diet who were hungrier and lost much less fat when they slept 5.5 hours a night than when they slept 8.5, and the short sleepers who were coached to sleep longer and ate about 270 calories a day fewer. The cheapest diet aid is a dark bedroom.
The loop runs both ways. Poor sleep sends you back to the processed food, and the late-night snacking that follows does the next night no favours. Fix one and the other gets easier.
What to cut first
If you are not sure what counts, Why People Fail at Weight Loss, above, has a quick test: an ingredients list with things no home kitchen has, such as high-fructose corn syrup, hydrogenated oils, emulsifiers, flavourings and colours.
Liquid sugar first. Fizzy drinks, juice, sweetened coffee. They deliver sugar fast with nothing to slow it, and the liver answers quickly when they go. 10 Eye-Opening Benefits of Cutting Out Sugar and Choosing Healthier Sweeteners has the 41 children whose sugar was swapped for starch at the same calories, and whose liver fat fell by almost half in nine days.
Then the grains and the packet snacks. This is where the carbohydrate switch and the cravings live, so give it the salt, the broth and the protein above.
Then the seed oils. Sunflower, soybean, corn and rapeseed oil, and the fried and packaged food made with them. Cook in butter, tallow or olive oil instead. This step brings the fewest symptoms, and its benefit takes the longest to arrive, for a reason the next section explains.
Each time, put meat, fish and eggs in the space. Taking something out is easier when something better is already on the plate. A kitchen cupboard hates a gap. Fill it before the biscuits do.
And if the obstacle is time or money rather than cravings, 10 Practical Strategies to Overcome Barriers to a Healthy Lifestyle has the more than five hours of free time Americans have a day on average, the $1.48 a day that separates the healthiest diets from the least healthy, and what meal planners eat.
The slow part: body fat
Your blood fats follow a change in diet fairly quickly. Your body fat does not.
In the 1960s, elderly men living in an institution were put on a diet high in seed-oil fats for up to five years. The share of linoleic acid, the main fat in seed oils, in their body fat rose from 11% to 32%, and the rise followed a curve with a half-time of 680 days. Body fat is an archive. It keeps records longer than your bank does. It holds the diet of the past few years, not of last month, and changes at that pace in either direction.
Across the United States, the linoleic acid in adults' body fat rose by 136% over half a century, in step with the rise of seed oils in the diet.
So the seed oils you stop eating today will take years, not weeks, to work their way out of your body fat. That is no reason to wait. It is the reason to start.
When food starts tasting right
This is where it gets easier, and the evidence is good.
Taste follows what you eat. The salt group from the start of this article ended up preferring less salt in soup and crackers. The Hidden Science of Sugar Cravings, linked below, has the people who cut their sugar by 40% for three months and then rated the same pudding about 40% sweeter than a comparison group did. Sweet things got sweeter, so less was enough.
This is why the occasional processed treat matters more than it seems: each one brings back the comparison that makes ordinary food taste dull. But one slip does not undo the work. Why Motivation Fails — and What Keeps Habits Going After It Does has the habits that kept forming through a missed day, and the moment where the real damage is done: deciding the week is ruined and eating accordingly.
The scales make that moment worse. One big carbohydrate meal refills the glycogen, along with the three to four parts water stored with it, so the number jumps overnight. That is water, not fat, and it leaves the way it came.
What to track
The usual blood test is a late alarm. Among 6,538 British civil servants, in the people who went on to develop diabetes, fasting glucose crept up for years and then climbed steeply only in the last three years before diagnosis. Insulin sensitivity had been falling for at least five.
So if you want numbers, look past fasting glucose. Fasting insulin tends to move earlier. HbA1c reflects your average blood sugar over about three months, the life of a red blood cell, so it shows little change in the first few weeks and is the one to recheck after three months. And hs-CRP is a marker of inflammation that often has to be asked for. For HbA1c, an takes a finger-prick sample at home and sends it to a lab.
Take a reading before you start and another after three months of steady change, and let whoever orders the test tell you what your numbers mean.
The cracker that tasted saltier
Go back to the salt group. Five months of eating less, and their taste had moved to meet them. Nobody told them to want less salt. They just did. The best willpower is the kind you no longer need.
That is what leaving processed food looks like when you know the timetable. The first days are blood sugar and caffeine. The first weeks are the switch away from carbohydrate. The middle weeks are the cravings. The slow part is body fat. And somewhere along the way, real food starts tasting like enough. Knowing which part is resisting, and why, is most of the battle.
This week, take out one sugary drink and replace it with water or a mug of salted broth, and keep it out until it stops tasting like a loss.
Fighting the cravings on willpower alone? How to Outsmart Cravings and Make Healthier Choices Without Relying on Willpower — what a craving is asking for, why protein quiets it, and how to stop without a willpower battle.
Is it always something sweet? The Hidden Science of Sugar Cravings — where a sweet tooth comes from, why it strikes in the evening, and ten ways to quiet it.
Know someone who gave up on cutting out processed food after a week? Send them this. The first week is the hardest, and it ends.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If you take medication for blood sugar or blood pressure, a big change in what you eat can change what you need, so get advice before you start.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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