Midmorning: The Leptin Lull
After we eat, our fat cells pump out leptin, the hormone of satisfaction. Leptin travels through the blood to the hypothalamus, signaling it to suppress hunger. Leptin also causes the brain to produce less dopamine, a neurotransmitter that’s released when you experience something pleasant. Dopamine is released with the first bite of food; it’s the little voice that urges us to eat more. Leptin quiets that impulse.
Production of leptin decreases two to three hours after a meal, signaling your brain that it’s time to eat again. This is why midmorning is an appetite danger zone.
10:30 a.m. Donna can’t concentrate. Since all she’s had to eat this morning is caffeine and carbs, her energy level and mood are low. She goes to the cafeteria for more coffee and picks up a chocolate croissant. Her brain gives her another shot of dopamine and noradrenaline, and it gets a big dose of insulin. It’s the wrong combination for a perimenopausal woman: Eating sugar and caffeine increases the hunger-pang hormone ghrelin and decreases the stop-eating hormone leptin, so it won’t be long before she’s hungry again.
Liz isn’t hungry yet, but she knows that by 11:00 or 11:30 she will be. So she has a small snack — a piece of low-fat cheese and half an apple — that has just the right amount of protein and complex carbs to keep her ghrelin level down.
In the 30 minutes since she ate her chocolate croissant, insulin has been coursing through Donna’s body, grabbing all the glucose and shoving it inside her cells. Unfortunately, this means her brain, which needs glucose to function, soon won’t get enough of it. Her stomach starts growling again, and this time her appetite center gets a double whammy: ghrelin spiking and leptin falling, both urging her to eat more.
Liz feels good. As she digests her snack, her ghrelin level drops rapidly, and satisfaction hormones are released. She stops thinking about food and focuses on her work.
Hormonal Hunger in the Afternoon
Early Afternoon: Beware the Feeding Frenzy
Donna is so hungry she has a headache. She considers ordering a salad, but the morning was rough, she’s behind in her work — and she wants comfort food. She orders a meatball sandwich, which comes with a side of fries. She eats everything. But she hasn’t conquered her appetite yet.
After the meal, her fat cells release leptin, telling her brain everything is okay. Her ghrelin level begins to decrease — but it will take about 20 minutes for her brain to get the message, so she still feels hungry. Donna buys a couple of cookies and a diet soda before heading back to work. Even drinking the diet soda is a bad move. Artificial sweeteners seem to switch on appetite the same way sugar does.
Liz, meanwhile, is tempted by lasagna, but knows it will make her feel sleepy. Her protein snacks have kept her ghrelin level from increasing, so she’s not starving and can override her craving for carbs; she orders the chicken Caesar salad with low-fat dressing on the side.
Midafternoon: The Cortisol Crash
Our level of cortisol, a stress hormone, naturally drops at this point in the day. For women in perimenopause, this is also the time when our testosterone level drops, and that can make us feel worn out and moody. Scientists think this is a major reason for weight gain at this stage of life, because feeling tired and cranky stimulates cravings for sweets and comfort foods. Another reason may be that in our mid 40s, the brain’s response to glucose can change dramatically, giving us uncharacteristic energy surges and drops, as well as cravings for sweets and carbs.
Liz yawns and thinks about eating a candy bar to get her through the last couple of hours of work. She knows it’s not a good idea, but her taste buds are clamoring for something sweet. She’s not hungry, so she decides to have a cup of mint tea and wait 30 minutes to see whether she still wants the sugar buzz.