In early 2021 the Biden administration asked Dr David A Kessler to co-lead Operation Warp Speed, responsible for all the vaccines and drugs used during the pandemic. As chief science officer of the White House Covid-19 Response Team he was spending 18 hours at his desk, seven days a week. “It took all I had,” he says, speaking from his home in Washington DC. “Nothing was more important than just getting the work done.”
And, “Food was my drug. I used food to change how I felt, to keep me going. If I was tired, I used food. If I was anxious, I used food.” When he left in 2023, the virus was “defanged” and Kessler had gained 40lb. He was over 200lb (14st 4lb) at his heaviest. “Things go awry.” It wasn’t a first. “I’ve gained and lost my body weight repeatedly over a lifetime.”
Kessler wasn’t unusual in impulsively overeating during the pandemic, and the rate of obesity in the UK rose during the first year of the crisis, contributing to the British Heart Foundation’s new findings that the nation’s heart health declined more quickly at the start of the 2020s than any other decade for more than 50 years. But now, after seven months on GLP-1 weight-loss drugs, he’s “sixty pounds lighter than I’ve ever been”. His features are, if he’ll forgive me, slightly gaunt, but he has halved the amount of “sick fat” he carries. He understands better than most why 64 per cent of British adults are estimated to be overweight or obese and why just 12 per cent of Americans are “metabolically healthy”. Driving this obesity epidemic is food that dysregulates our appetite and hooks us into a cycle of overeating and weight gain.
Ultra-processed, highly palatable foods like doughnuts are designed to addict us
GETTY IMAGES
As Kessler explains in his rigorous new book, Diet, Drugs and Dopamine: The new science of achieving a healthy weight, ultra-processed, highly palatable, energy-dense, high-glycaemic foods (he calls them UFFs: ultra-formulated foods) are designed to addict us. “They deliver just the right combination of fat and sugar, fat and salt, fat, sugar and salt — that potent trifecta — to trigger the reward circuits.” They change our brain chemistry, triggering compulsive eating and robbing us of the ability to feel full. They “steal our satiety”, Kessler says. “Losing weight is a process of treating addiction.”
It’s not lousy willpower making us fat. It’s the powerful effect of UFFs on our biology. Over the past fifty years, what we’re eating has caused “this insidious decline in health”. A study, just published in the American Journal of Preventive Medicine, suggested that about 18,000 deaths of people aged 30 to 69 could be prevented each year in Britain, if ultra-processed-food consumption were reduced. Only now are cardiologists, neurologists, endocrinologists, kidney specialists and oncologists waking up to the culprit, Kessler says.
“It’s not how big you are, it’s not how much you weigh, it’s the amount of toxic fat that we carry — the visceral fat in our mid-section.” Metabolically active, “it creates this inflammatory milieu in our bodies that is in the causal chain of these major diseases”. If we’re obese, we’re in a state of chronic inflammation. If we can reduce it, “we can dramatically change our health”.
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Until recently, that’s been near impossible. For most, trying to diet and exercise yourself slim is “an unmitigated disaster”, he says. “Very few people can keep weight off.” Why? “Our bodies are designed to hold on to fat for survival.” The body defends its highest weight. So once you’ve lost those pounds, it turbo-boosts your appetite (via the reward circuits) and slows your metabolism. “It’s a double whammy.” Keeping weight off is like holding an inflatable underwater, he says. “If I used to eat 2,000 calories, I’m going to have to eat 1,600 calories to maintain that weight because my metabolism slowed.”
But for those with the privilege of access, GLP-1 drugs have been a game-changer. They give you back your satiety. To overpower the brain’s addictive circuitry, you must strengthen the satiety system, Kessler says.
After Operation Warp Speed, his usual dieting method — low carb, high protein — was slow. “I lost maybe 6lb over a number of months.” When a kidney stone put him in an endocrinologist’s office, and weight-loss drugs were suggested, he agreed. He’s now 137lb with a BMI of 20, which “I never thought I’d achieve”.
GLP-1 drugs are markedly effective, he says. Yet, “they’re not a panacea. They are potentially dangerous and they are complicated. But they provide us with an opening to reverse the epidemic of chronic disease. There’s no magic in these pills.” Ultimately, “they get us to eat less”.
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Most aren’t entirely clear on how they work. “The companies haven’t fully levelled with the public. At least early on, they make you ill. They take you to the edge of nausea. And what’s the one thing that can change reward? And change the addictive circuits? If I push you towards or over the edge of nausea.”
GLP-1 drugs target the gut and our “aversive circuits”. Turns out, “adverse gastrointestinal events are part of the mechanism”. So a feature, not a bug. Feeling sick, unpleasantly full, ill, or worse, “you don’t feel like eating, they tamp down the reward circuits, they counterbalance that reward”. They also keep the food in your stomach for longer — also uncomfortable — “there’s a malaise associated with that”.
There can be serious medical side-effects, which Kessler worries about. Plus he senses that, on them, “a very significant number of people are eating less than 1,000 calories a day”. He recalls a family dinner — ricotta-stuffed organic roast chicken, sage & brown butter polenta. He barely managed a bite. “My gastrointestinal tract basically shut down. I couldn’t put anything in. I would become ill. These are very powerful drugs.” He says more research is needed as to how to safely use them. Why did he stop? “I had some abdominal pain, I got a little spooked.” After regaining some weight, “I went back on it for a while.”
These drugs only work while you’re on them, “but for one thing. They can tamp down the reward circuits so you can recondition yourself.” If you know you’ll feel ill if you eat again, “you’re going to condition yourself not to put food in your stomach. So learning how to eat less and eat better and change what you eat is the real task — it’s the gift while you’re on these drugs.”
They’ve certainly helped Kessler. He describes how at college he could only focus if the little fridge in his room was full of his favourite brands of chocolate cake and doughnuts. At night, he would “prowl for subs, pizza or wings”. He has vivid memories of his worries melting away, “as I slid headlong into the numb pleasure of overindulgence”.
Cravings would grip around 10pm. He’d feel “a pressing unease”. This disciplined, erudite man — former commissioner of the US Food and Drug Administration (FDA), a paediatrician, a lawyer, former dean of two medical schools, including Yale — would think, why can’t I control myself? Only overeating “rubbish” quieted the “food noise”. He says, “I became an alternate version of myself.”
His hope is to remove the stigma and shame people suffer when struggling with insatiable hunger and weight gain. Our reward circuits “were built for food”, he says. “It’s the first addiction, for survival reasons.” The stereotype of addiction as “extreme” or weak is false, he says. “Addiction happens in the normal functioning brain. Our brains are wired to focus on the most salient stimuli. Food has been formulated to become the most salient stimuli.”
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For appetite to be proportionate, our satiety and reward mechanisms must be in balance. And few understand how UFFs wreck that. Kessler calls them “psychoactive” — like any addictive substance, they hijack our reward circuits and change how the brain works.
“I would need food to change how I felt more than I needed food for fuel. And I think that is the hallmark of substances that affect the reward circuits,” he says. So, too, increasing our “hypersensitivity” to cues — be that hearing someone crunch crisps, boredom, upset — becoming locked in a pattern of craving, preoccupation, bingeing, withdrawal (for every high, there’s a dopamine low) and, often, self-loathing.
“Fifty years ago, I think I would have been a smoker,” he says. Now, he declares, UFF “is our new cigarette”. And he should know. As head of the FDA under George W Bush, and then Bill Clinton, Kessler took on the tobacco industry. (In Diet, Drugs and Dopamine his summary of their manipulative marketing and lies while knowing their products were killing people shocks anew.) It’s a brutal metaphor — is UFF that bad? “Look at the profound, profound harm it’s caused,” he replies.
I’m keen to know what he does now to maintain good health. He stresses that weight-loss drugs are only one tool. But crucially they facilitate a critical perceptual shift. “I used to look at these large portions of food and that was my friend. I look at that stuff now and I go, ‘That’s disgusting,’” he says.
One of his old haunts was a customised ice-cream sandwich place. Kessler would pile on M&M cookies, chocolate chips and sweets. After using GPL-1 he visited. He wasn’t tempted. “I don’t find certain foods as appealing. Again, there’s no magic. Those foods were sitting in my stomach for much longer periods of time.”
Importantly, he started exercising — in particular, weight training. “If you’re losing a significant amount of weight, you’re not just losing visceral fat, and you’re not just losing total body fat, you’re losing muscle.” By increasing muscle mass, strength training helps maintain a lower “set point” weight. “Walking is not enough,” he says.
We can boost satiety through nutrition, of course. Kessler describes pre-1936 Sardinian fare, one example of a Mediterranean-style diet. Food was often scarce, but what people ate (vegetables, legumes, goat’s milk, cheese, lard) was high in fibre, protein and fat, and wasn’t rapidly absorbed, so it was satiating. Kessler says that GLP-1 drugs mimic the natural effects of a high-protein diet. He mentions yoghurt, quality carbs and whole foods such as almonds.
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What’s his view on the approach of Robert Kennedy Jr, the US secretary of health and human services? “RK has certainly tapped into a populist sentiment. Everyone recognises that improving chronic disease is critical,” he says. “But I think what he is tackling and the way he is doing it, he’s gone about it all wrong. As laudable as discussing using food dyes and seed oils is, the culprit is toxic fat.” Plus, “The destruction associated with both his stand on vaccines and the associated biomedical infrastructure is just unacceptable.”
Back to the science. Kessler also wore a continuous glucose monitor for a few months to better understand his cravings. When he tried a low-calorie, high-protein, low-fat, low-carb diet, which flattened his glucose curve, “I was less under the sway of food.” Stabilising blood sugar and insulin is key to “recovery”, he says.
Kessler calls intermittent fasting “an especially effective timing strategy”. It helps you to push back against insulin resistance, rebalances the reward and satiety systems and can reduce carb and energy intake. “The real benefit is you’re not taking in as much food.” And “if food is not exerting that pull every 20 minutes or every hour or every three hours, that’s a great gift”. Some experts suggest 14 hours overnight should pass between meals. Your body uses its glycogen reserves then eventually shifts to fat burning.
Later I tell him that I like eating microbiome-friendly food, healthy protein and fat. He says that I’ve focused on what’s rewarding to me “and that will change your circuits”. But I confess that if I make gingerbread (basically, sugar insanity), I can’t stop thinking about it, keep cutting slices and within days I’m hankering for it. I have to go cold turkey on bitter chocolate.
Kessler smilingly responds that I suggested his cigarette analogy was “over the top”. In owning my gingerbread problem, “You’ve just normalised addiction. You said, ‘Hey, I see it in myself.’ We all have it.”
Diet, Drugs and Dopamine by MD Kessler (New River £22 pp384). To order a copy go to timesbookshop.co.uk. Free UK standard P&P on orders over £25. Special discount available for Times+ members