That’s an awful title for a post. Especially on a cooking blog, where the daily activities include decadent desserts, rich dishes, and a fair amount of indulgence. Yet “live thin or die trying” sometimes feels like the motto society has chosen for us. We are surrounded by images of what our bodies are supposedly meant to look like, and the pressure can become so familiar that we start applying it to ourselves.
I hope this blog has already made one thing clear: enjoying food and looking after yourself do not have to be enemies. But the desire to lose weight has created an enormous market for solutions, from magical pills and miraculous exercise equipment to the crown jewel of them all: diets. Before choosing one, it helps to understand where these ideas came from and what actually happens when we gain or lose weight.
In this first part, I’ll look at the history of dieting, explain some of the science behind it, and explore the limits of the numbers we use to describe a “healthy” weight. There will be a little biochemistry along the way. You knew that was coming.
A brief history of the modern diet
The word diet comes from the Greek δίαιτα (diaita), a word associated with a way of life. It was not simply the name of a temporary eating plan designed to make the scale move. That broader meaning is worth keeping in mind as we travel through the history of dieting.
People have connected food, body size, and health for centuries, although their explanations have changed considerably. The physician George Cheyne, for example, published An Essay of Health and Long Life in 1724. His writing reflects an early attempt to connect eating habits and daily activity with health. It also reminds us that advice about moderation was around long before calorie-tracking apps.
Attitudes toward body size have varied across cultures and periods. In some settings, a larger body suggested wealth and access to food; in others, thinness became fashionable. Medical concerns and social expectations have often become tangled together, which is one reason the history of dieting is more complicated than a simple march toward better science.
One influential figure in the nineteenth century was William Banting, a British undertaker who published Letter on Corpulence in 1863. Following advice from his physician, William Harvey, he reduced foods such as bread, sugar, potatoes, and beer while eating meals built around meat and other foods. His account became so popular that “Banting” became associated with dieting itself. The idea of restricting carbohydrates clearly did not begin with the modern low-carb movement.
Then, in the early twentieth century, another way of thinking about food entered the public conversation: counting its energy.
The calorie enters the conversation
The American physician Lulu Hunt Peters helped popularize calorie counting with her 1918 book, Diet and Health, With Key to the Calories. She did not discover energy balance, but she brought the idea into everyday discussions about eating and body weight. Food could now be considered in terms of how much energy it supplied, rather than only whether it belonged on a list of permitted or forbidden ingredients.
The basic principle is straightforward: over time, taking in more energy than the body uses tends to increase its energy stores. Taking in less tends to reduce them. That is the starting point. How much we eat, how much we use, and how our bodies respond are where things become more interesting.
Imagine driving to work and back every day. If the journey uses one gallon of fuel and you add one gallon each morning, the amount in the tank stays roughly the same. Add more than you use, and the extra accumulates. Add less, and you draw on what is already there. Our bodies are not cars, of course, and they do not behave like fixed-size fuel tanks. But the analogy gives us somewhere to begin.
A short detour through biochemistry
The body can obtain energy from carbohydrates, fats, and proteins. Glucose is an important fuel, but it is not the only one. Cells use metabolic pathways to transfer energy from these nutrients into ATP, a molecule that powers many cellular processes.
Digestible carbohydrates are broken down into simple sugars. Table sugar, or sucrose, supplies glucose and fructose; it does not simply become two glucose molecules during digestion. Starch is made of chains of glucose units. Through glycolysis and subsequent reactions, glucose can contribute to the production of acetyl coenzyme A, usually shortened to acetyl-CoA. This molecule connects several energy pathways.
Fatty acids can also supply acetyl-CoA through beta-oxidation. The body uses a mixture of fuels throughout the day, with the balance changing after meals, between meals, and during activity. It does not wait until every last carbohydrate has disappeared before using fat. Protein has many essential roles beyond energy production, although amino acids can also enter energy pathways after additional processing.
So what about “good” and “bad” carbohydrates? I find those labels a little too blunt. A carbohydrate’s chain length alone does not tell us how quickly a food will be digested or how nutritious it is. Processing, fiber, the food’s structure, the rest of the meal, and individual differences all matter. A piece of whole fruit contains sugars, for example, but it also brings water, fiber, and nutrients. That makes it a very different food from a sugary drink.
Whole grains, legumes, fruits, and vegetables can all fit into a healthy eating pattern. There is no need to treat every gram of carbohydrate as an enemy. Equally, calling something “complex” does not automatically make unlimited portions a good idea. The food and the overall pattern matter more than a slogan.
What calorie numbers can—and cannot—tell us
A food Calorie is a kilocalorie, abbreviated kcal. One kilocalorie equals 1,000 small calories. In everyday nutrition language, “200 Calories” and “200 kcal” refer to the same amount of energy. The terminology is confusing enough without making dinner into a unit-conversion exam.
For rough calculations, digestible carbohydrate and protein each provide about 4 kcal per gram, while fat provides about 9 kcal per gram. Fiber is different: it is not digested like starch, and its energy contribution depends on its type and how much is fermented by gut microbes. It should not simply be assigned 4 kcal per gram across the board.
Suppose someone’s weight is stable while their average intake is around 2,000 kcal a day. If their intake falls by 400 kcal a day and everything else initially stays the same, that represents about 2,000 kcal less over five days. The body must respond to that shortfall, including by drawing on stored energy.
What we cannot do reliably is divide that number by the energy content of pure fat and announce exactly how many days it will take to lose two kilograms. Body fat tissue is not pure dietary fat, and changes on the scale also reflect water, glycogen, lean tissue, and the contents of the digestive tract. Energy expenditure changes as body weight changes, and appetite can change too. A deficit is a useful concept; a guaranteed countdown to a particular weight is not.
The NIDDK Body Weight Planner uses a dynamic model to estimate weight changes over time. Even a more sophisticated model remains an estimate. It is a better starting point than assuming the body will respond at exactly the same rate indefinitely.
Activity belongs in this discussion as well. Returning to the car analogy, using more fuel changes the balance. But exercise is not simply a way to cancel out lunch, and the calories displayed on a machine are not precise measurements of what every person has used. Movement also matters for fitness, strength, and long-term health. A sustainable combination of eating habits and activity makes more sense than trying to create the largest possible deficit.
Is there such a thing as an ideal weight?
This is the million-dollar question. How much should we weigh? As a child, I remember hearing a simple rule: take your height in centimeters and subtract 100. At 184 cm, that would put me at 84 kg. Convenient? Certainly. A personalized assessment of health? Hardly.
Many formulas have attempted to turn height into a suggested body weight. The four below are often listed together, including on Calculator.net. They are useful for comparing approaches, but none can determine a person’s healthiest weight on its own. Their sex-specific equations reflect the categories used when the formulas were developed.
J. D. Robinson formula (1983)
- Men: 52 kg + 1.9 kg for each inch over 5 feet.
- Women: 49 kg + 1.7 kg for each inch over 5 feet.
D. R. Miller formula (1983)
- Men: 56.2 kg + 1.41 kg for each inch over 5 feet.
- Women: 53.1 kg + 1.36 kg for each inch over 5 feet.
G. J. Hamwi formula (1964)
- Men: 48.0 kg + 2.7 kg for each inch over 5 feet.
- Women: 45.5 kg + 2.2 kg for each inch over 5 feet.
B. J. Devine formula (1974)
- Men: 50.0 kg + 2.3 kg for each inch over 5 feet.
- Women: 45.5 kg + 2.3 kg for each inch over 5 feet.
These are adult reference formulas, presented here for heights above 5 feet (152.4 cm). They do not account for all the differences in body composition, age, or medical circumstances. The graph below compares their estimates across different heights. Agreement between several formulas does not turn their answer into a requirement for every person.
To compare the calculations, use the height-based weight calculator. Treat its results as estimates to put into context, rather than a verdict on your body.
Body mass index: useful, but limited
Body mass index, or BMI, offers another way to describe weight relative to height. Its roots lie in the work of the nineteenth-century statistician Adolphe Quetelet. Rather than producing one “ideal” weight, BMI places weight and height into a ratio:
BMI = weight in kilograms ÷ height in meters squared.
For example, someone who weighs 80 kg and is 1.80 m tall has a BMI of 80 ÷ (1.80 × 1.80), or about 24.7. You can use the CDC adult BMI calculator to calculate your own result. The CDC uses the following categories for adults aged 20 and older:
- Below 18.5: underweight.
- 18.5 to less than 25: healthy weight.
- 25 to less than 30: overweight.
- 30 or above: obesity.
Here is the important limitation: BMI does not distinguish fat from muscle or bone. It also does not tell us where body fat is stored. Two people can have the same BMI and very different body compositions. It is useful for screening and for studying populations, but an individual result needs context, including medical history, waist measurements, blood pressure, and other health indicators.
The next graph places the older weight formulas alongside a BMI reference range. It shows how different methods can produce different answers. It does not show that BMI has somehow corrected for muscle mass or bone density—it has not. And that childhood “height minus 100” rule? It remains a rough shortcut, however confidently we used to repeat it.
The rise of low-carbohydrate diets
Calorie counting was not the end of the story. Diets also began to focus on the proportions of carbohydrate, fat, and protein, and on whether changing those proportions could make weight management easier.
Robert Atkins helped popularize a modern low-carbohydrate approach with Dr. Atkins’ Diet Revolution, published in 1972. In its more restrictive phases, carbohydrate intake is low enough for the liver to increase ketone production from fatty acids. Other tissues can use those ketones as fuel. This metabolic state is called nutritional ketosis.
That is a change in fuel use, but it is not an escape from energy balance. Burning more fat during the day does not automatically mean losing more stored body fat, because some of the fat being burned may have come from the diet. Ketosis also does not mean that the body preferentially uses stored fat simply because it is “easier” to break down.
Low-carbohydrate diets can help some people manage appetite and reduce their overall intake. Early changes on the scale can also include water lost as glycogen stores decline. Adding carbohydrates back can restore some of that glycogen and water; it does not automatically mean that an equivalent amount of body fat has returned. Nor does beginning a low-carb diet lock someone into it forever.
The useful questions are practical ones: Is the eating pattern nutritionally adequate? Is it manageable? How does it affect the individual’s health? A low-carb label alone cannot answer them. People taking glucose-lowering medication also need to coordinate substantial dietary changes with their clinician, because medication requirements may change.
A crowded diet landscape
The diet world is full of competing systems. Some focus on counting calories or points. Some emphasize particular foods and portions. Others restrict carbohydrates, limit eating windows, or exclude entire food groups. These categories overlap much more than the advertising suggests.
When I first wrote this article in 2014, I pointed readers toward diet rankings as one way to compare the options. Rankings change, however, and a place on a list is not the same as evidence that a plan will suit everyone. I would rather ask whether it supports good nutrition, fits someone’s circumstances, and can be maintained beyond the first burst of enthusiasm.
The DASH eating plan, for example, emphasizes vegetables, fruits, whole grains, and a range of protein foods while limiting sodium and saturated fat. Mediterranean-style patterns also offer room for vegetables, legumes, whole grains, fish, and olive oil. Neither requires us to abandon the pleasure of cooking. As a Greek, I am particularly relieved about the olive oil.
It is also worth being precise about restrictive diets. Paleo, raw-food, and low-carb diets are not interchangeable. Paleo generally excludes grains and legumes but can include carbohydrate-rich fruits and vegetables. Raw-food patterns can also contain plenty of carbohydrate. Avoiding a particular group of foods does not tell us the complete nutritional picture.
And medical diets deserve a separate conversation. Celiac disease requires a strict gluten-free diet; “Paleo” is not a substitute for learning how to avoid gluten and cross-contact. Similarly, a low-carb diet is one possible approach for some people with diabetes, not a universal recommendation. The appropriate plan depends on the person and their treatment.
Epilogue: a way of eating, not a temporary punishment
After all the formulas, fuel analogies, and diet names, I keep returning to that broader meaning of δίαιτα: a way of life. An eating pattern has to work in the kitchen, at the table, and in ordinary daily life—not just on paper.
When this article was first published, the USDA’s MyPlate illustration was a familiar guide to food groups. I have kept it below as part of the original article. It is a visual starting point, not a universal prescription for exact portions.
Rather than assigning the same daily quantities to everyone, think about the building blocks of meals:
- Vegetables and fruit, with variety across the week.
- Whole grains and other fiber-rich carbohydrate sources.
- Protein foods such as beans, lentils, fish, eggs, poultry, nuts, or other suitable choices.
- Dairy foods or nutritionally appropriate fortified alternatives, where they fit.
- Fats such as olive oil, nuts, and seeds, in portions that suit the overall eating pattern.
The amounts—and sometimes the choices—will differ from person to person. A balanced eating pattern does not guarantee a particular body size, and health cannot be read from appearance alone. It can, however, give us a more useful foundation than treating food as a daily test of willpower.
In the posts that follow, I want to look more closely at different approaches to dieting, how they fit into real life, and what the evidence actually supports. And, of course, there will be recipes along the way. This is still a cooking blog.
Sources and further reading
- George Cheyne: An Essay of Health and Long Life (1724), Wellcome Collection.
- William Banting’s original pamphlet and its history, Royal College of Surgeons.
- Lulu Hunt Peters: Diet and Health, With Key to the Calories.
- OpenStax: carbohydrate metabolism and lipid metabolism.
- FDA: calories on the Nutrition Facts label and labeling guidance, including fiber energy factors.
- NIDDK: research behind the Body Weight Planner.
- CDC: what BMI measures and its limitations.
- Hall and colleagues (2015): dietary fat restriction versus carbohydrate restriction in a controlled feeding study.
- NIDDK: treatment for celiac disease.
Originally published July 15, 2014. Revised October 30, 2026, for clarity, formatting, and scientific accuracy.