4. Food Addiction?
Debate of the validity of “food
addiction”
Is it based on the environment?
Strength of willpower?
New research has started to show
evidence for a biological basis of
addictions to high fat and sugary
foods
Similar neurological changes occurred
in rats that were addicted to
substances of abuse, such as opiates
and cocaine
5. Sugar Addiction
One study done by Avena et al., 2008 deprived rats of all food
for 12 hours and then allowed them to have access to both
regular chow food and a sugar solution for 12 hours
This created an intermittent availability of sugar intake and it
was continued for 1 month
The rats started to show similar signs of addiction and
withdrawal during periods of sugar abstinence:
“Bingeing” – the rats started to drink excessive amounts of the
sugar solution, especially when it first became available during the
day
Similar to drug addiction when users build and tolerance and
escalate their use to continue feeling the same euphoric effects
When compared to rats who had 24 hour access to sugar, the rats
with intermittent access ate the same amount of sugar within a
shorter timeframe, consisting of larger, but fewer meals
6. Sugar Addiction
Opiate-like “withdrawal” – when the rats were deprived
of sugar, they displayed similar signs of opiate withdrawal,
such as:
Somatic signs – teeth chattering, forepaw tremor, head shakes
Behavioral anxiety – spending less time than control rats in an
open and exposed arm of a maze
Behavioral depression – decreased escape efforts and more
passive floating in a forced-swim test
“Craving” – the rats showed an enhanced motivation to
obtain the sugar by:
Pressing a lever 23% more after a 2 week period of sugar
abstinence compared to when the experiment was first over
Suggests that the motivational impact of sugar persists and
enhances even during periods of abstinence
7. Sugar Addiction
“Cross-sensitization” – rats showed different behaviors
when exposed to other drugs of abuse:
Hyperactivity – when given low doses of amphetamine (0.5
mg/kg that have no effect on naïve rats), the rats that were fed
intermittent sugar showed hyperactive behaviors and locomotor
cross-sensitization
Similar effect s when given cocaine, suggesting similar pathways
in the mesolimbic dopaminergic neurotransmission and could be
an explanation for poly-substance abuse
Increased intake of another drug – rats that were fed
intermittent sugar and then forced to abstain showed a 9%
increase intake of alcohol
Similar results have been found with an increase in self-
administration of cocaine compared to control groups and could
be an explanation for the “gateway effect”
8. Neurobiological Changes
The researchers also found significant changes within the brain
during and after intermittent sugar intake:
Increase in release of dopamine in the nucleus accumbens during
sugar intake
After continued use, increase in D1 receptor binding and decrease in
D2 receptor binding similar to results found in cocaine abuse
Changes within the opioid system, showing a decrease in enkephalin
mRNA expression in the nucleus accumbens (thought to lead to a
decrease in the release of dopamine through mu and delta
receptors) similar results in human subjects that were cocaine-
dependent
During abstinence, there was a decrease in extracellular dopamine,
followed by release of acetylcholine mimics the response that
occurs during morphine, nicotine, and alcohol withdrawal
Impact on dopaminergic, cholinergic and opioid systems, with
similarities to other drugs of abuse
9. Fat Addiction?
Similar studies have been done with high fat diets, which showed rats
bingeing on the food, but did NOT display the same signs of opiate-like
“withdrawal” that were seen with sugar
In addition, rats on the high sugar diet tended to compensate for their
bingeing by decreasing their intake of normal chow food, and had normal
weights
Rats placed on high fat, or high sugar and fat combination diets tended to
gain weight
Could this explain our obesity epidemic? Much of the American diet is a
combination of fat and sugar, such as fried doughnuts and cupcakes
Could the sugar be accounting for the addiction and fat be accounting for
the weight gain?
10. Neurofunctional Imaging Studies
PET studies have shown a
decrease in the number of
dopamine D2 receptors in
obese patients as well as
those addicted to cocaine,
methamphetamine,
alcohol, and heroine
Inverse relationship
between obese BMI (42-
60) and the amount of
dopamine D2 receptors,
but not in control group
plays a larger role in obese
subjects
11. Gastric Banding Surgery
Places an inflatable
band around the
stomach to restrict
food intake
Size of stomach can be
adjusted easily
Lowest mortality rate
Least invasive
Weight loss does not
come as fast and is
not as permanent as
other options
12. Roux en-Y gastric bypass
A small pouch is
created from the
top portion of the
stomach, which is
then connected to
the jejunum
A majority of the
stomach and
duodenum are
bypassed
Faster and longer
lasting weight loss
More complications
such as ulcers,
internal hernias,
and malabsorption
14. Post-Surgery Findings
Studies have found a change in alcohol metabolism after
bariatric surgery
Patients get intoxicated faster and take longer to become
sober
Another study found an increased percent in alcoholism in
bariatric surgery patients 6-10 years after the surgery
Possibly because food and drugs compete for the same
reinforcement sites in the brain through the mesolimbic
dopaminergic pathway
If a patient undergoes bariatric surgery and can no longer
satisfy their cravings by bingeing on high fat and sugary
foods, they may turn to other substances to activate the
same pathway addiction transfer?
15. Addiction Transfer
Some professionals have started to coin this term
for when a person replaces one compulsive
behavior for another
We see the concept occurring after bariatric
surgery, as substance abuse is not commonly
found in the obese population, but there is an
increase after bariatric surgery
Also seen in some recovering alcoholics who
develop a dependence on nicotine or caffeine –
same phenomenon?
Not an accepted clinical or scientific term
Not a common outcome of bariatric surgery, but
increased risk of problematic substance abuse
16. Addiction Transfer
Patients have lost the weight, but still have not dealt with their
emotions that caused them to turn to food for comfort in the first
place
Feel a “void”, so turn to another substance for the comfort that
food used to provide
“The weight loss surgery didn’t cause me to be an alcoholic. I’m
born an addict” – bariatric patient
One study found that cognitive-behavioral group therapy was
helpful for patients post-surgery, but they also thought that
individualized therapy would be helpful as well
More studies need to be conducted on the most effective therapy
for bariatric patients
17. Conclusion
Significant neurobiological and behavioral changes occur
when given excessive, intermittent high fat and sugar
diets
These parallel the changes found in those with drug
addictions, such as cocaine, amphetamines, and heroine
Patients who undergo bariatric surgery may have an
increased risk of developing another addiction or
compulsive behavior
“Addiction transfer” is not a clinical term, but the theory
is supported by many clinicians and can be seen across
different groups of people
