Standard American Diet (SAD) Skews Biological Rhythms and Gut Bacteria

by Mike Mutzel


It's been long known that obesity and diabetes is linked with imbalanced gut bacteria and skewed circadian clock genes. But, for the first time in human history, scientists at Rush University in Chicago demonstrated how the standard American diet (SAD) in animals not only causes deleterious shifts in circadian rhythms but also negatively impacts gut bacteria.

 Balance Your Biological Clock, Reclaim Your Metabolism, and Burn More Fat

As we’ve discussed before, circadian clock genes regulate many aspects of our biology with the rise and fall of the sun. For example, cortisol peaks in the morning and melatonin and growth hormone peak at night. This is due to the fine tuning of the circadian clock system.

SAD Diet Disturbs Circadian Clocks Leading to Leaky Gut and Imbalanced Gut Bacteria

Disturbances in this delicate system have been linked to obesity, diabetes, cancer, inflammation, and excessive intake of processed foods. Although researchers have previously shown that circadian clock disruption can cause leaky gut, no scientists have linked a skewed circadian clock with gut bacteria imbalances. This state of imbalance is also linked to physiological imbalances that have been ascribed to circadian clock miss-matches.

Since gut bacteria play such a critical role in maintaining the status quo of the intestinal barrier, these Chicago-based scientists sought to determine if the SAD diet could pivot the circadian clock out of biological alignment and cause imbalanced gut bacteria, in animals. They gave mice the diet that many Americans eat every day: a high-sugar, high-fat diet (29 percent and 35 percent, respectively).

To be sure that it was the diet that induced disruption of the circadian clock, thus causing the gut bacteria imbalances, the scientists first used artificial light to skew the animals’ circadian clocks. Although the research team sufficiently pivoted the clock out of alignment, no changes in the gut bacteria were observed.

However, after eating a SAD diet for 12 weeks, DNA microbial analysis revealed drastic shifts in microbial communities in these animals. Specifically, there was an increase in bacteria belonging to the “fat” phyla (Firmicutes, Proteobacteria) and a reduction in bacteria belonging to the skinny phyla (Bacteroidetes). Such shifts were not found in the control group (standard rodent chow diet).

Additionally, the research team reported an increase in the abundance of pro-inflammatory Ruminococcus bacteria.Also, the animals fed the make-shift SAD diet demonstrated significant circadian clock imbalances to the point that the test group started eating at different times compared to the control group.


Both circadian clock disruption and gut microbial imbalances have independently been linked with inflammation and metabolic disorders. This new study reveals how a standard American diet can indeed cause both .It first skews the circadian clock network and then imbalances the gut. Previous studies have reported sleep disturbances (circadian clock disruption) in persons with irritable bowel disease (IBD), adding credence to this animal model study.

With a majority of Americans sleeping less than seven hours per night and simultaneously eating a diet rich in processed sugars and fats, it’s not shocking that over 68 percent of American adults are overweight and/or obese.

What we really need to do is this: Aim for eating a diet rich in colored vegetables, fruits, nuts, seeds, and wild-caught fish and game. Avoid packaged and processed foods. Aim to be in bed by 10 pm with the lights off and strive for 8 hours of sleep per night.

Further Reading

Chapter 8 of Belly Fat Effect unveils the whole story about the circadian clock system and metabolism, fat burning, appetite, and much more.


Join the conversation


  2. Hi I'm interested in computer courses to study, today I spoke to someone from one of the unis I was interested in one of the courses were more about designing and the other practical and more technical fixing and support the system. I'm really interested in that. Its called computer enterprising. .. . But I want to apply to more but I get confused as every university calls the computer courses a different name. So i'm unsure if its software , or computer science , IT , IS with business. I think it could be IS with business what I'm interested in but I'm unsure. In some of the modules in the enterprise one has : information systems,computer programming ,data management , software testing , human computer interaction. developing internet applications supporting the systems kinda thing. . Which computer course would include that sort of things? Its one of the practical and technical I want I'm not interested in designing. And can anyone tell me from this which computer courses is more like the one i described is it Information technology with business or something else? And is Computer science based on designing the applications? and not the more practical.

  3. This is really interesting, You're a very skilled blogger.
    I've joined your feed and sit up for looking for extra of your wonderful
    post. Additionally, I have shared your website in my social networks

  4. Good day! I know this is kinda off topic however I’d figured I’d ask.
    Would you be interested in exchanging link or maybe guestt
    writing a blog article or vice-versa? My blog covers a lot
    of thhe same topics as yours and I think we could greatly benefit from each other.
    If you’re interested feel free to shoot me aan email.
    I look forward to hearing frm you! Terrific blog by the way!

Leave a Reply