Scary-skinny NICOLE RICHIE’s wild and wacky food fixations are causing a mountain of stress in her marriage!

The 32-year-old TV personality and fashion mogul refuses to eat anything but the organic fruits and vegetables from her own home garden and eggs from her backyard chickens.

But a friend of the star – whose new reality series, “#CandidlyNicole,” debuts on VH1 in July – revealed that Nicole’s obsession with watching what she eats is driving her hubby, Joel Madden, crazy.

“Joel likes to treat their kids to a burger or an ice cream cone once a week, but Nicole won’t allow it anymore,” revealed the source. “She even brings her self-harvested produce and hard-boiled eggs from her hens to restaurants and insists that chefs make her meals with them.”

Nicole insists that eating by her rules is the only way to ensure that her family – including daughter Harlow, 6, and son Sparrow, 4 – isn’t being exposed to dangerous pesticides or genetically modified foods. She currently grows apples, blueberries, lemons, strawberries, butter lettuce, arugula, snap peas, tomatoes, carrots, broccoli, cauliflower, kale, spinach, mint, thyme, oregano and sage at the family’s California home.

While the produce is healthy, Nicole’s limited diet of less than 1,400 calories a day isn’t helping the weight-challenged star put on the pounds. And board certified weight-loss specialist Dr. Craig Title, who has not treated Nicole, warns that an unsupervised low-caloric diet can have side effects including muscle-wasting, weakening of bones, fatigue and electrolyte abnormalities.

As The ENQUIRER reported earlier this year, Good Charlotte rocker Joel, 35, isn’t happy about his wife getting thinner and insisted she gain 10 pounds – which never happened. The 5-foot-1 reality star reportedly weighs 85 pounds, just two pounds more than when she reportedly sought treatment for anorexia and substance abuse in 2007.

“Although she has always denied eating disorders, Nicole’s friends can’t help but wonder whether she’s slipping into the grips of one now,” the source noted. “Joel is at his wits’ end over her weird food ways and even more concerned that she’s passing on her quirky habits to their kids.”