"Stop Eating Hot Dogs and Lose 13% Belly Fat in 8 Weeks?" The Truth Behind the Diet of Simply Reducing "Ultra-Processed Foods"

"Same calories, but only the belly slims down" — could such a convenient story be real?

"I've been walking and eating more vegetables, but my weight just won't budge…"
Many people must be familiar with this classic diet frustration.

A study from South Dakota State University, introduced by the German news site op-online, presented a challenging message to this dilemma: "The focus might be on 'degree of processing' rather than calories."op-online

Overview of the Study

- Subjects: 36 elderly individuals, average age 72, with mild obesity tendencies
- Duration: Total of 18 weeks (8 weeks + break + 8 weeks)
- Diet:
- Meat-based group (mainly lean pork)
- Plant-based group (mainly lentils, beans, peas)
- Both groups followed "nutritionally exemplary" menus according to the "Dietary Guidelines for Americans (DGA)"
- Common rule:Significantly reduced ultra-processed foods (UPF)

The research team prepared over 12,000 meals, reducing the ultra-processed foods that originally made up about half of the participants' diets to around 15% of daily energy intake, and managed them thoroughly by having participants eat at home.South Dakota State University

The key point here is that the "nutritional balance was the same for both groups." The amounts of protein, fats, carbohydrates, and dietary fiber were adjusted, with the only difference being **"how industrially processed the foods were."**News-Medical

Results: Calories "didn't decrease" but "naturally decreased"

After 8 weeks, participants experienced the following changes.op-online

• Daily calorie intake: Average of about −400kcal

• Weight: Average about 4kg loss

• Abdominal fat:about 13% reduction

• Insulin: Approximately 20% decrease

• Insulin sensitivity: About 25% improvement

• LDL cholesterol: 10-12mg/dL decrease

• Inflammation markers (such as CRP): Significantly decreased

There were no instructions to restrict calories, nor were there any prohibitions on what to eat.
Yet, just by reducing the proportion of ultra-processed foods, everyone naturally ate less.

Moreover, the effects were almost the same for both the meat-based and plant-based groups.
It was shown that it's not a simple matter of "losing weight because you're vegetarian" or "gaining weight because you eat meat," but rather the key is **"how much the food retains its original form."**op-online

Hormonal Changes: Could "Satiety" and "Energy Utilization" Be Rewritten?

Interestingly, changes were observed not only in weight but also in hormones.op-online

• Hormone regulating energy metabolism FGF21 increased by up to 50%

• Hormone related to appetite leptin decreased

These suggest that the body switched to a mode where it efficiently uses energy and avoids overeating.
Researchers pointed out that "it's insufficient to only look at nutritional balance; the degree of food processing must also be considered."South Dakota State University

So, what exactly are "ultra-processed foods"?

The "Ultra-Processed Foods (UPF)" targeted in the study can be roughly described as follows.News-Medical

• The original form of ingredients is hardly retained

• Contains numerous additives like flavorings, colorings, emulsifiers, and preservatives

• Ready to eat or just add hot water or microwave

• Contains ingredient names that you wouldn't typically have in your kitchen

Sausages, hot dogs, instant noodles, snack foods, pastries, sugary cereals, sugar-laden soft drinks…
In the U.S., such UPFs are said to account for about half of an adult's daily calorie intake and about 70% of the total food supply.South Dakota State University

Social Media Quickly Caught Fire and Buzz

When this study and the articles introducing it spread, various reactions erupted on social media (the following are summarized impressions of typical voices).

Positive Camp: Those Who Found Hope

• "I failed at calorie counting and low-carb diets, but I might be able to just 'reduce packaged snacks.'"

• "Losing 4kg in 8 weeks is intense. I'll start by cutting out pastries and juice."

• "It's realistic that there's no difference between vegetarian and meat. I want to challenge my whole family to 'cut out UPFs.'"

Skeptical Camp: Those Taking a Calm View

• "Isn't 36 subjects too few? And they're all elderly, right?"

• "I heard part of the funding comes from the pork industry (National Pork Board), so I want to be careful not to see it as pork-biased."South Dakota State University

• "The simple binary of UPF = bad is dangerous. Choices about food also involve price, time, and culture."

Realists: Voices Concerned About Living Costs

• "I get it, but unprocessed foods are expensive and time-consuming…"

• "For working couples with kids, completely eliminating UPFs is impossible. If just 'reducing' them has an effect, that's a relief."

These reactions seem to reflect the reality of balancing "cost and effort" with "health risks" in Japan as well.

"8 Weeks of Success" and "The Reality a Year Later"

The op-online article pointed out another important aspect.op-online

About a year after the study ended, when participants' eating habits were tracked, many had returned to ultra-processed foods.

• During the study: UPF ratio about 13-15%

• One year later: UPF ratio about 44% (approaching the original 50%)

Consequently, the improvements in weight and some metabolic indicators also diminished.The familiar diet adage, "It doesn't matter unless you can keep it up for life," surfaced here as well.

Still, Three Insights from This Study

1. Focus on "how food is made" rather than "what and how much"
   Besides calories and sugar content, asking yourself, "Can I imagine the original form of this food?" might be a big hint.

2. Don't Aim for Zero or 100
   In this study, UPFs weren't completely eliminated but remained at about 15%.
   "Switch from convenience store meals five days a week to cooking at home two days a week."
   "Reduce sweet café lattes from daily to once every three days."
   Even such "loose shifts" might be meaningful.

3. Possibility of Turning Off the "Overeating Switch" at the Hormonal Level
   Changes in hormones related to appetite and metabolism suggest a strategy of "making it easier to lose weight through mechanisms, not willpower."op-online

Five Steps to "Reduce Ultra-Processed Foods" You Can Start Today

1. 3-Second Check of Ingredient Labels
   - A lineup of unreadable katakana or alphabet letters
   - A parade of sugar, high-fructose corn syrup, sweeteners
   Such foods should be downgraded from "daily" to "occasional."

2. Make One Meal a Day a "Non-Packaged Staple"
   For example,

   • Frozen pizza → Rice + natto + egg

   • Cup noodles → Udon and vegetables simmered in a pot
     It doesn't have to be the "ideal health menu."Just shifting the main role from a package to a pot or cutting board is enough.

     ##HTML_TAG_