How Many Meals a Day? What Changes When You Track Meals

This post is about how often you eat. When in the day you eat is a different question with its own trials, and it has its own post: does meal timing matter when counting calories to lose weight. The two overlap at breakfast, and I link across where they do.

Where the six small meals advice came from

It started with surveys. Several studies in the 20th century found that people who reported eating more often weighed less, and that looked like a reason to graze. In 1997 a team led from INSERM, the French medical research institute, reviewed every study they could find on meal frequency and energy balance. Many of the surveys found no relationship at all. The ones that did find one all pointed the same way, more meals and less weight, but the authors called the evidence "at best very weak" and said it "almost certainly represents an artefact".¹

They gave two reasons. People who have gained weight often change how they eat afterwards, cutting meals to lose it, so the pattern can follow the weight rather than cause it. And people with more weight tend to under-report what they eat, which makes their eating look sparser on paper than it is.¹ That second point comes back later in this post, because it applies to your own food log as well as to a survey.

The surveys have not settled down since. A study of 50,660 Seventh-day Adventists in North America, followed for about seven years, found the opposite pattern: people who ate one or two meals a day saw their BMI fall slightly each year compared with people who ate three, and people who ate more than three saw a relative increase.⁹ A smaller American study found that people who had lost weight and kept it off ate more snacks a day than people who were still overweight, 1.9 against 1.5.¹⁰ Both are observational, with self-reported eating, and their authors frame them as associations. Data that point one way in one decade and the other way in the next are the reason the question had to go to trials.

Six meals against three, on the same calories

The metabolism half of the claim rests on the energy it costs to digest food. Each meal raises your energy use for a few hours, so more meals sounds like more burning. The question is whether many small rises add up to more than a few big ones. The 1997 review found that the short-term studies split, with most showing nothing, and that studies measuring a whole 24 hours in a calorimeter or with doubly labelled water found no difference between nibbling and gorging.¹

Two calorimeter studies since then show it directly. In one, women with a BMI over 25 lived in a sealed metabolic chamber on about 1,000 calories a day, served either as six meals or as two. Energy expenditure over 24 hours was 10.00 megajoules on six meals and 9.96 on two, a difference the authors could not tell from zero. When the women were allowed extra food on top, they did not eat more on one pattern than the other.² In Colorado, 15 lean adults spent a day in a whole-room calorimeter on three meals and another day on six, with the same food and calories. Energy expenditure and fat burning did not differ. Hunger and the desire to eat, rated through the day, were higher on six meals.⁴

Those were days, not months. An Ottawa trial ran for eight weeks. The 16 adults with obesity who finished it all ate about 700 calories a day under their needs, either as three meals or as three meals and three snacks. Together they lost 4.7% of their body weight. Between the groups there was no difference in fat loss, appetite ratings or the gut hormones measured.³ Sixteen people is a small trial, but it is the exact question someone counting calories wants answered.

What 22 trials add up to

Two meta-analyses have pooled the trials. A 2015 analysis of 15 studies first appeared to find that eating more often helped: more fat lost and more lean mass kept. When the authors ran a sensitivity analysis, the benefit turned out to be the product of a single study, and they ended by saying the findings "need to be interpreted with circumspection".⁵

A 2020 network meta-analysis from Freiburg, which lets trials of different frequencies be compared with each other, took in 22 randomised trials with 647 participants, all comparing different numbers of meals on the same calories for at least two weeks. Two meals a day came out slightly ahead: about 1.0 kg less body weight than three meals and 1.3 kg less than six, which the authors graded as moderate certainty. One meal a day ranked first for weight, but the comparisons involving it that the abstract reports are either uncertain or graded very low certainty. How much people ate did not differ by meal frequency. The authors' conclusion is that "there is little robust evidence that reducing meal frequency is beneficial."⁶

Read together, the two analyses put six small meals and three ordinary ones in the same place, with a small edge for fewer that the trials have not firmly established. A kilo over a trial is real but modest, and it came from trials that fixed everyone's calories, so it says little about the larger effect frequency might have on how much you choose to eat.

Does eating more often keep hunger down?

This half of the claim matters more if you are eating in a deficit, and here the studies disagree.

In one feeding study, 13 men with overweight or obesity ate the same calories as three meals or as six across an 11-hour day. Six meals gave lower fullness through the day than three, whatever the protein content. Higher protein did raise fullness. The authors concluded that their data challenge the idea that more eating occasions improve satiety.⁷ Reviewing the controlled feeding studies a year later, two of the same researchers found that going above three meals a day had "minimal, if any" effect on appetite and food intake, while going below three, dropping one or two meals, made appetite control worse.⁸

The longest trial ran the other way. In a six-month weight loss programme in Pennsylvania, 51 adults with the same calorie target were told either to eat three times a day or to graze, eating at least 100 calories every two to three hours. The grazers did eat more often, 5.8 times a day against 3.2. Their hunger ratings fell over the six months. Across everyone, reported intake fell from about 2,200 to about 1,270 calories a day and average BMI from 35.5 to 30.6, and the two groups did not differ on either.¹¹ The authors call it a pilot, and they say eating more often reduced hunger but may not be related to bigger reductions in intake or weight.

My reading is that the number of meals does not do much to hunger on average, and that its effect differs between people enough that the only test that settles it for you is a few weeks of your own log.

One or two meals a day

The pooled trials give fewer meals a small edge, so it is worth looking at what the low end costs. A pilot trial at the US Department of Agriculture had healthy, normal-weight middle-aged adults eat their full maintenance calories as one meal a day for eight weeks and as three meals a day for eight weeks, in random order. Their weight stayed within 2 kg throughout. On one meal a day they were significantly hungrier and lost some fat mass, and their blood pressure and their total, LDL and HDL cholesterol all went up.¹² The authors call it a pilot, and note that the time of day may have affected the outcomes.

At the two-meal end, a Prague trial gave 54 people with type 2 diabetes the same reduced-calorie diet for 12 weeks as six meals, and for another 12 weeks as two, breakfast and lunch only. They lost 2.3 kg on six meals and 3.7 kg on two.¹³ It was open-label and in people with diabetes on medication, and the two-meal arm also moved all the eating into the morning and early afternoon, so it changed when people ate as well as how often. The meal timing post covers the trials that move calories earlier without changing the number of meals, and they split on whether it changes weight loss.

Snacks are the meals people forget to log

Frequency does one definite thing to a food log. Every extra eating occasion is one more you have to remember to enter.

In Cambridge, 33 women spent 24 hours in a metabolic facility where everything they ate was covertly measured, then reported what they had eaten. Their meals were reported accurately. The energy from snacks eaten between meals was significantly under-reported, and the authors identify forgotten snacks as the main cause of the under-reporting they found, in women with and without obesity.¹⁴ That was a recall at the end of a day, not logging as you go, but the gap it found is the same one a food tracker for weight loss has to close.

A New Zealand study measured the size of it against doubly labelled water, which gives a person's actual energy use. Ordinary 24-hour recalls underestimated it by 17% in men and 13% in women. When people also looked through photos from a camera they had worn the day before, the gap shrank to 9% and 7%, mostly because they remembered 265 foods they had left out, often snacks.¹⁵

And snacks are a large share of what people eat. In US national surveys, the share of adults who snacked rose from 71% in 1977 to 1978 to 97% in 2003 to 2006, and snacks went from 18% to 24% of daily calories.¹⁶ A quarter of the day is a lot to lose from a log. The other big sources of logging error, the packet and the portion, are in how accurate calorie tracking apps actually are.

What the evidence does not settle

• Whether two meals beat three in the long run. The pooled edge is about a kilo, graded moderate certainty, from trials that lasted weeks to months.⁶
• Whether one meal a day is safe to sustain. The one controlled trial in healthy adults found higher blood pressure and cholesterol after eight weeks, and the pooled evidence on its benefit is uncertain or very low certainty.⁶¹²
• Hunger. The feeding studies say more meals do not help and fewer can hurt; the six-month grazing trial says grazers got less hungry.⁸¹¹ Neither tells you which kind of eater you are.
• The surveys. They have pointed both ways, and the 1997 review explains why they cannot be trusted to settle it.¹⁹¹⁰
• Whether real-time logging fixes the snack gap. The under-reporting studies used recalls. I could not find a study that measured how many snacks go missing from an app that people log in as they eat.

What a meal tracker app shows about how often you eat

I can only speak for my own app. MyPlate has no breakfast, lunch, dinner or snack slots. Every meal you log, from a photo or a sentence, goes into the day's list with a time, which you can change if you log it later, and the daily total is all the calorie target cares about. The home-screen widget shows how many meals you have logged today, and it counts every entry, so a coffee and a biscuit at four o'clock count as two.

That makes it neutral about frequency, which is where I think the evidence leaves it. It will not tell you to eat six times or twice. It cannot tell you about a snack you did not log, and a photo of a handful of crisps is still an estimate, not a measurement. What the list does show, after a couple of weeks, is your real pattern: how many times you actually ate, and whether the days you went over were the days with the extra eating occasions.

How many times a day to eat when you track meals

Here is the procedure I would use, gap and all. Take a 35-year-old woman, 165 cm and 68 kg, moderately active. MyPlate's weight-loss goal puts her at 1,811 calories a day, which is 85% of its maintenance estimate. As three meals that is about 600 each. As three meals of 500 and two snacks of about 150, it is the same total. The trials say both will move the scale about the same if she hits the number.³⁶ So the choice comes down to which one she can hit.

• Start with the pattern you already eat. Changing how often you eat and how much at the same time makes it hard to tell which change did anything.
• Log every eating occasion as it happens, snacks and drinks included. Logging after the fact is where snacks went missing in the studies above.¹⁴¹⁵
• After two weeks, look at the days you went over. If they are the days with long gaps followed by a large evening, try adding a planned snack in the gap. If they are the days with lots of small extras, try fewer, larger meals.
• Give each pattern two or three weeks against your weekly average weight, not a single weigh-in.
• Be careful with one or two meals a day. Fewer meals made appetite worse in the feeding studies, and one meal a day raised blood pressure and cholesterol in the one trial that tested it.⁸¹² If you take medicine for diabetes, talk to your doctor before cutting meals.
• Do not let fewer meals turn into too few calories. The NIH guidelines describe low-calorie diets of 1,000 to 1,200 calories a day for women and 1,200 to 1,500 for men,¹⁷ and MyPlate never sets a target below 1,200 for women or 1,500 for men. Compressing the day into one meal makes it easy to fall under that without noticing.

If a protein target is part of your plan, the number of meals also decides how it is split. Whether that matters is the subject of does protein per meal matter when tracking macros.

If calorie tracking is making you anxious, or you are logging to punish a meal rather than to understand it, stop and talk to a doctor or a registered dietitian. What the research says about who that is most likely to be is in can calorie tracking cause an eating disorder.

Common questions

Eat as often as keeps you at your number

Eating more often does not raise your metabolism. In the trials the number of meals barely moved the scale once calories were held equal, and the small edge for fewer meals is not firm.⁵⁶ What it can change is when you get hungry and how much goes unlogged. Pick the pattern you can keep at your target, log every eating occasion including the small ones, and let a few weeks of your own log decide whether to change it.

Sources

1. Bellisle F, McDevitt R, Prentice AM (1997). Meal frequency and energy balance. British Journal of Nutrition, 77 Suppl 1:S57-70. Read on PubMed →
2. Taylor MA, Garrow JS (2001). Compared with nibbling, neither gorging nor a morning fast affect short-term energy balance in obese patients in a chamber calorimeter. International Journal of Obesity and Related Metabolic Disorders, 25(4):519-528. Read on PubMed →
3. Cameron JD, Cyr MJ, Doucet E (2010). Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet. British Journal of Nutrition, 103(8):1098-1101. Read on PubMed →
4. Ohkawara K, Cornier MA, Kohrt WM, Melanson EL (2013). Effects of increased meal frequency on fat oxidation and perceived hunger. Obesity, 21(2):336-343. Read on PubMed →
5. Schoenfeld BJ, Aragon AA, Krieger JW (2015). Effects of meal frequency on weight loss and body composition: a meta-analysis. Nutrition Reviews, 73(2):69-82. Read on PubMed →
6. Schwingshackl L, Nitschke K, Zähringer J, et al. (2020). Impact of meal frequency on anthropometric outcomes: a systematic review and network meta-analysis of randomized controlled trials. Advances in Nutrition, 11(5):1108-1122. Read on PubMed →
7. Leidy HJ, Armstrong CL, Tang M, Mattes RD, Campbell WW (2010). The influence of higher protein intake and greater eating frequency on appetite control in overweight and obese men. Obesity, 18(9):1725-1732. Read on PubMed →
8. Leidy HJ, Campbell WW (2011). The effect of eating frequency on appetite control and food intake: brief synopsis of controlled feeding studies. Journal of Nutrition, 141(1):154-157. Read on PubMed →
9. Kahleova H, Lloren JI, Mashchak A, Hill M, Fraser GE (2017). Meal frequency and timing are associated with changes in body mass index in Adventist Health Study 2. Journal of Nutrition, 147(9):1722-1728. Read on PubMed →
10. Bachman JL, Phelan S, Wing RR, Raynor HA (2011). Eating frequency is higher in weight loss maintainers and normal-weight individuals than in overweight individuals. Journal of the American Dietetic Association, 111(11):1730-1734. Read on PubMed →
11. Bachman JL, Raynor HA (2012). Effects of manipulating eating frequency during a behavioral weight loss intervention: a pilot randomized controlled trial. Obesity, 20(5):985-992. Read on PubMed →
12. Stote KS, Baer DJ, Spears K, et al. (2007). A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. American Journal of Clinical Nutrition, 85(4):981-988. Read on PubMed →
13. Kahleova H, Belinova L, Malinska H, et al. (2014). Eating two larger meals a day (breakfast and lunch) is more effective than six smaller meals in a reduced-energy regimen for patients with type 2 diabetes: a randomised crossover study. Diabetologia, 57(8):1552-1560. Read on PubMed →
14. Poppitt SD, Swann D, Black AE, Prentice AM (1998). Assessment of selective under-reporting of food intake by both obese and non-obese women in a metabolic facility. International Journal of Obesity and Related Metabolic Disorders, 22(4):303-311. Read on PubMed →
15. Gemming L, Rush E, Maddison R, et al. (2015). Wearable cameras can reduce dietary under-reporting: doubly labelled water validation of a camera-assisted 24 h recall. British Journal of Nutrition, 113(2):284-291. Read on PubMed →
16. Piernas C, Popkin BM (2010). Snacking increased among U.S. adults between 1977 and 2006. Journal of Nutrition, 140(2):325-332. Read on PubMed →
17. National Heart, Lung, and Blood Institute, NIH (1998). Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. NIH Publication 98-4083. Read the guidelines →

The formulas and limits behind MyPlate's own numbers, with their citations, are on the health sources page.